The Tanakh was mainly written in Biblical Hebrew, with some portions (notably in Daniel and Ezra) in Aramaic.
Some time in the 3rd century BCE, the Torah was translated into Koine Greek, and over the next century other books were translated as well. This translation became known as the Septuagint and was widely used by Greek-speaking Jews and, later, by Christians. It differs somewhat from the Hebrew text as standardized later (Masoretic Text).
From the 800s to the 1400s, Rabbinic Jewish scholars known as the Masoretes compared the text of all known Biblical manuscripts in an effort to create a unified standardized text; a series of highly similar texts eventually emerged, and any of these texts are known as Masoretic Texts (MT). The Masoretes also added vowel points (called niqqud) to the text, since the original text only contained consonants. This sometimes required the selection of an interpretation, since words can differ only in their vowels, and thus the meaning can vary in accordance with the choice of vowels to insert. In antiquity other variant readings existed, some of which have survived in the Samaritan Pentateuch, the Dead Sea scrolls, and other ancient fragments, as well as being attested in ancient versions in other languages.
Versions of the Septuagint contain several passages and whole books additional to what was included in the Masoretic texts of the Tanakh. In some cases these additions were originally composed in Greek, while in other cases they are translations of Hebrew books or variants not present in the Masoretic texts. Recent discoveries have shown that more of the Septuagint additions have a Hebrew origin than was once thought. While there are no complete surviving manuscripts of the Hebrew texts on which the Septuagint was based, many scholars believe that they represent a different textual tradition from the one that eventually became the basis for the Masoretic texts.