In the 3rd century BC, Jewish religious books were translated from the Hebrew into another language. The resultant book is known as the Septuagint. In which language is the Septuagint written?

What we today call the Bible, is not one book, but a collection of many shorter books, written by different authors over centuries and brought together in one volume.

The Old Testament is a collection of ancient Jewish holy scripture and the New Testament is just a small part of the early Christian writings. But who chose which books would make it into the Bible and which would be cast aside?