Administrative Assistant / Secretary: A Simple Guide To Office Equipment

Telephones
Telephone service has come a long way since it was invented in the late 1800s. In the early days, telephone service was primitive and selective. Not everyone had a telephone, nor could you call everyone or everywhere. Only towns that put up the poles and ran the wires had service, and even then, many people had to share a telephone line.
Today, telephone service is taken for granted. Businesses use voice mail and computerized answering machines to take messages, to network computers across town or across the country, and to send fax transmissions to offices around the world. Let’s start with the basic business services that allow you to call across the street.

Private Branch Exchange
You may have seen in old movies a switchboard operator struggling with a tangle of wires and plugs. Today’s larger businesses have replaced the switchboard operator with a private branch exchange (PBX) system. A PBX is a computerized telephone management system that is ideal for a company with many employees and individual phone extensions. It allows a single telephone number for a business to be accessed at the same time by numerous outside callers. As each call is received, it is automatically routed to the appropriate extension via a touchtone phone or with the help of a receptionist or operator.

Multi-Line Telephones
A multi-line telephone system is often the preferred choice in a small business. It allows you to answer an incoming call from anywhere in the office and to route it to another telephone at the touch of a button. If one line is being used, you can access another line to make an outgoing call.

VoIP Telephones
Voice over Internet Protocol (VoIP) is a technology that is rapidly growing in popularity in many businesses today. This technology allows for sending telephone audio over the Internet rather than traditional telephone lines. The advantage is low-cost local and long-distance telephone service.
The IP phones look just like normal phones, but instead of the normal RJ-11 phone connectors, they use an RJ-45 Ethernet connector and are connected to your computer network. IP phones have all the software and hardware to handle IP calls.

Other Business Telephones
A wide variety of other available business telephones combine telephone service with computer operations. Many of these more sophisticated telephones are equipped with special features, such as buttons and lights to designate different lines. More modern telephones use computer-like LED (light-emitting diode) displays to designate and select lines as well as to indicate the number dialed. Others are programmable to store frequently called numbers in the telephone’s memory. Some have speaker telephones built in to free up one’s hands while talking. Still others have automatic redialing, intercom capabilities, and built-in answering machines.

Voice Mail
When you’re away from your desk and no one else can cover your telephone, it’s important that you use a voice-mail system. You don’t want to miss critical calls for your boss or yourself. Customers now expect the use of such devices, no matter what size company you work for.
Computerized voice-mail systems accept incoming calls and route them to various voice mail boxes for each employee. All messages are stored in the company’s phone system computers or by the telephone company.

Integrated Messaging
Integrated messaging is a service that allows voice-mail messages to be received as email attachments using email software such as Microsoft Outlook. The message normally includes caller-ID information such as the phone number or email address of the person calling you. You can listen to your messages by opening the email and clicking the attached audio file.

Special Telephone Services
Many telephone companies have a variety of special services that enhance the performance of your business telephone system, no matter which model you have. These services may vary from one part of the country to another. Here is a description of some of the more common services available:
- Call waiting is useful for individuals who and for small businesses that have only one incoming telephone line. When you’re on one call, you are alerted by a tone that another incoming call is waiting. If you wish, you can put the current call on hold and switch to answer the new incoming call.
- Select call waiting permits only the calls the user has programmed into the telephone to beep you in the call-waiting mode.
- Call forwarding allows you to redirect calls intended for your telephone to another telephone of your choice—ideal when you or your boss must spend extended time at another location.
- Select call forwarding enables you to program your telephone with a list of only those people you want to be able to contact you at the forwarding number.
- Three-way conferencing allows you to call more than one person at a time so that three or more people can participate in the same conversation.
- Caller ID shows you on a visual display the name and number of the person calling. Caller ID lets you use your telephone like a pocket pager, enabling you to decide whether to take the call, return it later, or ignore it.
- Busy number redial continues to dial a busy number automatically until the line is free. The telephone then alerts you when the line is ringing.
- Selective call acceptance allows you to program your telephone with a list of only those people you want to contact you. When a person on that list calls, the call rings through to your telephone. No other calls are allowed to get through.
- Voice message enables callers to leave a message that you retrieve later, just like an answering machine. Voice message is similar to voice mail; however, no special equipment is required at a user’s location.

Toll-Free Numbers
One long-distance service can benefit your company’s customers: a toll-free number, sometimes called a “Watts” line. As the owner of an 800 number, your company pays for all incoming long-distance charges. A toll-free number is an expense, true, but it’s more than just a convenience for your distant customers. It can be a selling point in whether your company makes the first sale at all.
Because of the demand for toll-free numbers, telephone companies have made a variety of other three-digit prefixes available in addition to 800, including 888, 878, 877, 866, and 855.

900 Numbers
The 900 prefix is often associated with information lines that require the caller to pay a per-minute fee for the time on the call. This fee is charged to the caller’s telephone bill and paid to the owner of the 900 number. Some small businesses involved in mail order have tried using 900 numbers, but often it is reserved for technical help, not for customers who want to order a product.

Teleconferences
One way to reduce travel costs associated with meetings is to use teleconferencing. Teleconferences can be scheduled in advance with a long-distance carrier. With a reservation, you can link up different callers from around the country at the same time.
There are two basic ways to conduct a teleconference. In the first, each caller dials a special telephone number at a designated time and is connected to the group teleconference one by one. In the second, an operator calls and connects each individual to the teleconference. The cost of the teleconference includes a setup fee and an hourly fee for each caller along with the long-distance charges for each individual.
Teleconferences are often combined with Web conferences, where attendees are not only connected via the telephone but also view a presentation on the Web.

Fax Machines
While faxes are increasingly being replaced by email, there are still millions of fax machines in use, and millions more faxes are sent annually.
Today’s fax machines are faster and more versatile than ever. There are even products available that tie your fax machine to your office telephone’s voice messaging system. Those products make it as easy to check for fax messages when you’re out of the office as it is to check for voice messages.

Computer Fax
In addition to dedicated fax machines, there are also fax modems available for personal computer systems. A fax modem will connect your computer to the phone lines to send and receive data and allow your computer to send and receive faxes.
To send a fax, you first compose the document on the computer electronically. Then, without having to print out the document and take it to a fax machine, you access the software that comes with the fax modem and transmit the document just as a regular fax machine does. Incoming faxes are stored in your computer’s memory like a graphic. You can read the fax using the software or print it out with your printer.

Office Computers
Companies of all sizes routinely use personal or desktop computers in the office. Computers allow employees to be more productive by automating many repetitive tasks, such as word processing, billing, and filing. They come in a wide variety of configurations for both Microsoft Windows and Apple Macintosh operating systems.
When most people use a PC, what they are really using is a computer system. The computer itself may be no larger than a single integrated circuit chip soldered to a circuit board inside the computer’s case. However, the user interfaces with a variety of other elements that together make up the computer system. These elements, called peripheral devices, include the keyboard, monitor, mouse, disk drives, and printer.

A true computer system usually consists of five elements:

1. An input device, such as a keyboard or mouse, that allows you to communicate with the computer.

2. An output device, such as a monitor or a printer, that allows the computer to communicate back to you.

3. A processor that allows for the manipulation of your data. The central processing unit (CPU) is the brains of the computer system.

4. A storage system, such as a hard disk drive, that allows you to save your work electronically.

5. Software that provides instructions for the computer in the form of programs.

Hardware
How you operate your computer and what type of work it can perform depend on how your system is equipped. From the outside, the computer is just a case to house the electronic components. There are a variety of different computer designs, such as the desktop system, laptop, or tablet computer.
All computers have a power switch on the system unit, located on the front of the case or on the back. Depending on which brand of computer you use, there will also probably be drives mounted inside the system unit and USB (universal serial bus) connectors for connecting various devices such as a keyboard and mouse. Looking at the back of a typical PC, you will normally see USB ports for the printer, keyboard, and mouse, a network port, and a video port for the monitor.
The computer’s operating system and programs are stored on a hard disk drive that is mounted inside the system unit. In addition, most computers have a DVD drive. Each disk drive is given a letter, number, or name so that it’s easy to load and save information to or from a particular drive location. On Microsoft Windows computers, the hard drive is called drive C. The DVD drive would be called drive D. On Apple Macintosh computers, the drives are given names or labels.
The PCs are usually designed to be expandable. For this reason, it’s possible to remove the case should you need to get inside to install a new component. Many people are afraid to open the computer case, yet the more familiar you are with your computer, the better able you will be to troubleshoot little problems that arise from time to time. Computer repairs and upgrades are simple skills to acquire, yet they are invaluable, especially in terms of time saved.
Inside the system unit of a typical computer you will see a metal box, which is the computer’s power supply. This transformer converts the power from the wall outlet into electricity that can be used by the computer. You’ll see the hard disk drive that is mounted inside the case. And you’ll see the motherboard, which occupies most of the inside of the computer. This large circuit board contains various chips and your processor. On the motherboard, you will see various slots for plug-in expansion boards. Expansion boards are available for a variety of purposes. They easily plug into the motherboard expansion slots so you can add a device such as a high-performance video card.
Other key components in your computer are the memory and the processor. The amount of memory your computer has determines the amount of workspace available for data. For example, if you are working with a large word-processing document or a large accounting program with a lot of data, you might eventually see messages on your monitor screen that the computer is running low or is out of memory. Most computers allow for upgrading the amount of memory. For most Windows and Macintosh computers, you can add to the computer’s memory by plugging in memory chips, which are what provides your computer’s memory. Memory chips can be plugged into slots on the motherboard of your computer to increase system memory. Your computer will likely have between two and four slots for memory and usually come with between 4 to 8 gigabytes (GB) of memory.
Computer performance and speed are determined mainly by the type of processor chip included with your computer. Also important in evaluating speed and performance is the clock speed of your processor. Clock speed is the speed at which messages from the computer processor travel to other parts of the computer, such as the disk drives, hard drive, monitor, and printer. Speeds ranging up to several gigahertz (GHz) are available today.
The key point to remember when you’re choosing a company computer is that better speed and performance usually translate into greater productivity. Therefore, an investment in a good computer system can help you do more in less time.

Memory
Computer memory is often very confusing to new computer users, because it implies that the computer will remember your data automatically. However, this is not the case: If you create a document with a word processor but don’t save it and then turn off your computer, the document will be lost. Unfortunately, most computer users learn this lesson the hard way. Long-term storage of data is handled by the hard disk drive, not by the computer’s memory.
Your computer’s memory is that area where programs and data are temporarily copied from a CD, DVD, or hard disk drive so that you can use them. Moving programs and data into memory is called loading or, on some systems, opening. It is just like taking a document out of a file cabinet and putting it on your desk. Unlike this analogy, however, when a computer loads a program or a document into memory, it only takes a copy—leaving the original intact on the disk. You can modify the original by saving your latest work with the same name as the original, or you can retain the original and keep a new version by saving the new version with a slightly different name.
Random access memory (RAM) is the area of memory where your programs and data are loaded. Memory is measured in terms of bits, bytes, kilobytes, megabytes, and gigabytes. Electronically, the RAM in your computer is made up of lots of little electric switches that are turned on or off. For programming purposes, “on” is given a numerical value of 1, and “off” is given the numerical value of 0. Therefore, programs and data are represented as lots of 1s and 0s. Each character in the alphabet is represented by a special code made up of 1s and 0s. Each group of eight 1s and 0s is called a byte; 1,024 bytes equal a kilobyte, 1,024 kilobytes equal a megabyte, and a gigabyte is 1,000 megabytes.
The same is true for numbers and graphics on your monitor. Some computers use a 32-bit system. That means that it takes a combination of 32 1s and 0s to form each character or graphic. Other more advanced computers use 64-bit systems.
Another way some computers access even greater amounts of memory is to use virtual memory. Computers can use part of the computer’s hard drive as if it were extra RAM. Virtual memory is slower than RAM memory and is used primarily when multiple programs are loaded and running at the same time. The program not being accessed by a user can be temporarily swapped to virtual memory.
Read-only memory (ROM) is another type of memory that is built into the computer and cannot be changed by programs. ROM chips contain a permanent set of instructions that support the overall operation of the computer. Essentially, they function automatically and require little attention from most computer users.

Computer Input Devices
In order to use computers, you need some way to communicate with them. This process is known as input. There are many types of input devices. Probably the most common is a keyboard. By simply typing on a keyboard, you send information to the computer for processing. In order to see what it is you have typed, most computers use a monitor. As characters are typed on the keyboard, they appear on the monitor screen.
Among the most familiar devices for input are game controllers such as joysticks. These devices allow a game player to communicate information to a computer informing it of key decisions necessary to play a game. A similar device is a mouse, a hand controller that is used in some software applications and operating systems for a variety of different computers. A mouse is used to select menu choices and to move a cursor, or pointer, around on the monitor screen. Similar to a mouse is a track ball. Many small portable computers use touchpads, since the operator may be using the computer where there is no desktop available for a mouse.
Another useful form of input designed originally for disabled individuals is voice recognition. Voice recognition and natural language speech systems interpret the human voice into signals that a computer can understand as input. Voice recognition systems are now popular and can be used to select menu items in software and, in some cases, even to create text for a word-processing document or spreadsheet.
For graphic artists and designers and others who need to input precise drawings, a special drawing device called a graphics tablet is available. A graphics tablet consists of a plastic board containing a grid of fine electrical wires. A special drawing pen is used to draw. When the pen comes into contact with the grid of wires, information on the location of the pen is sent to the computer in order to create a graphics image on a monitor screen.
Another input tool used by graphic artists is the scanner. There are various models available. Some you hold in your hand; other desktop models operate much like a copy machine. With the desktop version, you place an original document into the scanner, and the scanner copies an image of the document or graphic into the computer’s memory. When the document is text, special optical character recognition software is often used. This software takes the images input from a scanner and compares them against various text styles in memory. It then translates the scanner image into text for your word processor.
Finally, digital cameras can be used to acquire digital images that can be transferred into a computer and used in desktop publishing applications.

Computer Output Devices
When you work with a computer, most of your attention will be focused on output devices. This is where you see the results of your work. The most common output devices found on computer systems are the monitor and the printer. Both output devices are available in many different models.

The Monitor
Monitors display information by painting the screen with tiny dots of color called pixels. Today, there are several different types of monitors to fit various needs. Most are flat-screen liquid crystal display (LCD) monitors that come in different screen sizes.
The crispness of the monitor’s picture is measured in dot pitch, refresh rate, and resolution. Dot pitch is the distance between pixels. The better the dot pitch, the better the monitor can display lines and curves. The refresh rate is the speed at which the monitor repaints the screen. Refresh rates are measured in Hertz (Hz). A low refresh rate will produce a noticeable flicker on the monitor. Resolution is the screen image size that can be displayed on the monitor as measured in horizontal and vertical pixels.

The Printer
Along with video display monitors, the other most popular form of output for a computer system is a printer. Printers produce a hardcopy paper version of what is on your display screen. There are several different types of printers available.
Ink Jet Printer   Ink jet printers produce letter-quality output by spraying ink through a series of tiny nozzles onto the paper to form each letter. Ink jet printers can print in black and white and in color. In fact, some ink jet printers can produce photographic-quality output that rivals traditional photographic film prints.
Laser Printer   Perhaps the most successful and popular method of producing letter-quality text is with a laser printer. Although laser printers are more expensive than ink jet printers, their quality and speed have made them popular among all types of computer users. Laser printers function similarly to copy machines. A graphics image of the computer output is sent to the laser printer, which also has a computer processor. The laser printer then uses a laser to display an image on an electrically charged drum surface. Once the charged surface comes into contact with a powdered or liquid toner, the toner sticks in the image areas and falls off the non-image areas. When paper comes into contact with the drum, the toner is transferred to the paper, producing an image.
Color Laser Printers   Recent advances in color printing have resulted in laser printers that use multicolored toners for producing color output.

Printer Performance
The performance of a printer is determined by its resolution, memory, and speed. Printer resolution is the sharpness of the image the printer can produce on paper. Resolution is measured in dots per inch (dpi). For draft-quality text printing, a dpi setting of 300 is sufficient. For letter-quality printing, a dpi setting of 600 is good. For photographic-quality printing, a resolution of 600 dpi or better is needed.
The dpi settings affect the speed of the printer. Most ink jet and laser printers can print three to six pages per minute, depending on the type of image. Photographic-quality images may take much longer. Laser printers tend to be the fastest printers available.
Printers have built-in memory that helps speed up the printing process. If you print large documents or documents with complex graphics, having additional printer memory will enhance printing speed.
Another device for reproducing computer output is a plotter, or large format printer, which draws the computer output in large format. This is often used in architectural and design offices.

Storage Devices
The ability to store, search for, and retrieve specific information from permanent data storage media is ideal for helping secretaries organize the department or company—and keep it organized. Using the computer’s electronic filing system, you should see a great time savings for yourself as well as an increase in your productivity and efficiency in day-to-day business activities.
A computer stores your work in two areas, one temporary and one permanent. The temporary storage is your computer’s memory, its RAM. We’ve already discussed computer memory, but it’s important to remember that information stored in RAM is stored only as long as the computer is turned on.

The Hard Drive
The main permanent storage device is the computer’s hard drive (sometimes called a fixed disk), which can be either internal (mounted inside the computer case) or external (in its own case connected to the computer via a cable). A hard drive is actually a stack of disks coated with a magnetic coating, similar to audiotape or videotape. Information is saved on a hard drive much the same way a song is recorded on audiotape. The computer’s electronic signals are recorded on the magnetic hard drive disk, and when you want the information back, the hard drive “plays back” those signals. Saving information on a hard drive is called writing to the drive; playing information back is called reading. It is also possible to erase information on a drive, which is called deleting.
Disk storage capacity is measured in units called bytes. As previously discussed, a byte is made up of 8 bits of information. One thousand twenty-four bytes is a kilobyte, or K for short. A megabyte is 1,024 K. One thousand megabytes is a gigabyte (often called a “gig”). One thousand gigabytes is a terabyte. Hard drives can store billions of bytes.

Tape Backup
One specialized storage medium is available solely for the purpose of making backups. Tape backup drives use a cartridge tape to back up your hard drive and all your data. A tape backup drive is much slower than a hard drive, so it’s not very useful for normal day-to-day use as a storage medium. However, special software combined with a tape backup drive can automatically back up your data periodically so you’ll also be protected in the event of hard drive failure.

CD-ROM and DVD-ROM
Another data storage medium is a CD-ROM. This system uses a compact disk to store computer data. Approximately 600 megabytes can be stored on one CD-ROM. If you have a CD-ROM drive that can create—or “burn”—CDs, you can also use it for making backups of your data. These drives are often called CD Recordable (CD-R) or CD Read and Write (CD-RW) and can store approximately 600 megabytes of data.
Making the move from the entertainment center to the computer are DVD-ROM drives. These drives can store several gigabytes of data and are often also used for viewing DVD movies on your computer. DVD recordable (DVD-R) and DVD Read and Write (DVD-RW) drives are also available. They can record DVD data disks that can store 4 to 9 gigabytes of data.

Flash Drives
Flash drives are small portable devices that can connect to the USB port on your computer for storing and transferring data from one computer to another. Flash drives are about the size of your car keys and can store data for ten years or more without being plugged into a power source. These inexpensive devices come in a variety of sizes ranging from a few megabytes up to several gigabytes.

Laptop Computers
Many offices use small laptop computers in place of desktop computers to give employees mobility and flexibility when using their PCs. With a laptop, everything is combined into one unit: CPU, monitor, hard drive, DVD-ROM, modem, and network card, as well as other devices like speakers and microphones. Laptop computers can be upgraded with larger hard drives and additional RAM. You can connect them to printers, a phone line, and an office network, or to an external monitor, keyboard, and mouse. One nice feature of a laptop computer is the built-in battery. This battery will power the computer for several hours without needing to be connected to a power outlet.
While you can connect an external mouse to a laptop computer, a variety of built-in pointing devices are available. Most laptops use a touchpad with buttons or a pointing stick positioned next to the G and H keys that resembles the eraser of a pencil.
When you are in the office, some laptops can be connected to a port replicator or docking station. When connected to one of these expansion units, you can use an external monitor, keyboard, and mouse just like a desktop computer system.

Tablet Computers
Tablet computers are mobile computers that feature a touchscreen and Wi-Fi or cellular network connectivity. Tablet computers include models like the Apple iPad, Samsung Galaxy, or Microsoft Slate. These lightweight computers allow you to use your finger rather than a mouse to make selections. Some models do not include a keyboard, and instead an on-screen keyboard is used.

Maintaining Your Computer
For the most part, there is little you need to do to maintain your computer system. However, as for any machine, there are a few things you can do that will help your computer last longer and operate smoothly.

ScanDisk
This is a utility that comes with your computer that can detect and fix hard disk errors that cause performance problems. In the latest versions of Windows, this utility is called CHKDSK. These utilities run automatically if a computer loses power unexpectedly. You can also run these utilities periodically to check the condition of your hard disk drive. To run the utility in Windows 7 and earlier versions, double click MY COMPUTER, then right-click your hard disk drive. From the pop-up menu, click PROPERTIES. On the Properties window, click TOOLS, then in the Error-Checking section, click CHECK NOW.
In Windows 8, access the DESKTOP and click the FILE EXPLORER icon. Then right-click your hard disk drive. From the pop-up menu, click PROPERTIES. On the Properties window, click TOOLS, then in the Error-Checking section, click CHECK NOW.

Disk Defragmenter
As you use your computer, the files you save get divided and spread in different available spaces on your hard drive. The more spread out or fragmented they get, the more the performance of your computer is affected. A disk defragmenter recombines files and resaves them in one continuous location. This reorganizes your hard drive and improves disk efficiency.

Disk Cleanup
As you work with various documents, print, view Web pages, and so forth, temporary information gets stored on your computer. These temporary files can grow in size and eventually squeeze out room for other things. It’s a good idea to delete these files from time to time.

Backing Up Your Data
If your hard drive fails, you could lose all your data. Since your hard drive is like a very large filing cabinet filled with important and often confidential data about the business you work for, protecting that information is very important. Therefore, you should back up your hard drive frequently by making copies of all data onto an external hard drive, a network drive, a backup tape, diskettes, a CD-R, a CD-RW, a DVD-R, or a DVD-RW.
There are also a variety of online backup services available where you can pay a monthly or annual fee and have a backup copy of your files stored offsite. These services allow you to make periodic automatic backups over the Internet.

Popular online backup services include the following:
- My PC Backup: www.mypcbackup.com
- Just Cloud: www.justcloud.com
- Backup Genie: www.backupgenie.com
- iBackup: www.ibackup.com
- Zip Cloud: www.zipcloud.com
- Sugar Sync: www.sugarsync.com
- Mozy: www.mozy.com
- Crash Plan: www.crashplan.com
- Carbonite: www.carbonite.com
- SOS Online Backup: www.sosonlinebackup.com

Copy Machines
Another essential office tool is the copy machine. Although the advent of word-processing typewriters and personal computers has reduced reliance on copiers to some extent, because you can make additional paper copies by printing out duplicates, many documents that do not originate from your word processor or PC require copies.
Many small businesses use a local print shop for copies; however, considering the amount of time lost going back and forth to the shop and the convenience and relative cheapness of having your own copier, purchasing or leasing a copier for the business may be a good idea.
Copiers and laser printers function similarly. They are often referred to as “nonimpact printing.” Rather than have a hammer strike a ribbon to produce type on the page like a typewriter, copiers use a photographic process involving static electricity.
When you place a document to be copied inside a copy machine, a very strong light is projected on the original. The image of the original is then projected to an electrically sensitive rotating drum. The dark and light areas of the original affect the electric charge on the print drum. After being exposed to the original, the copier drum turns through a powder called toner, which sticks to the electrically charged areas. The drum then comes into contact with a fresh piece of copier paper, transferring the toner to the paper, thus creating a copy.
More advanced copiers magnify the projection of the light from the original to the copier drum, thus enlarging or reducing the size of the reproduction. Many copiers use microprocessors to store images and to automate many of the functions such as sorting, collating, and making two-sided copies. With the use of multicolor toners, color copies can be produced. Other copiers have automatic document feeders, paper trays, sorters, and even built-in staplers. The choice of features makes for a wide range of prices.

Binding Systems
Binding systems are used to create professional-looking bound reports, presentations, and proposals. One of the most common systems is the plastic comb binding system. This is an ideal solution for binding standard letter-size documents in-house. The system includes a punch press that punches up to twenty sheets of 20-pound paper per punch and binds documents sheets with two-inch plastic binding combs. A paper guide and ruler are used to align sheets accurately.

Laminators
Laminators are often used to preserve photographs and to create quick reference cards, place mats, badges, and ID cards. A paper document is placed into a clear plastic lamination pouch and then run through the heated laminator, which seals the document in a protective hard plastic covering.

Overhead Projectors
Overhead projectors and video projectors are often used in meetings and presentations to large groups. With an overhead projector, presentation materials are copied or printed on clear plastic transparency pages called foils or transparencies. The transparencies are then placed on the light table of the overhead projector, and a powerful light passes through the transparency and projects an image on a screen. The transparencies can be written on during a presentation for everyone in the meeting to see.
Video projectors are often used to display videos, television images, or computer data. With a video projector, presentation slides can be created using a program such as Microsoft PowerPoint. The slides are then displayed on a screen by the video projector. When the presenter wants to change slides, the mouse button is clicked or the space bar on the keyboard is pressed.

Paper Shredders
As a security measure to protect sensitive documents, paper shredders are used to destroy draft copies and old documents as an alternative to throwing them in the trash. Paper shredders vary in size from small models that fit on top of a trash can to large free-standing models.