Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, or possibly earlier. It has the longest documented history of any Indo-European language, spanning at least 3,400 years of written records. The Greek language holds a very important place in the history of the Western world. Greek is also the language in which many of the foundational texts in science,literature and philosophy were originally composed. The phonology, morphology, syntax, and vocabulary of the language show both conservative and innovative tendencies across the entire attestation of the language from the ancient to the modern period.

The division into conventional periods is, as with all such periodizations, relatively arbitrary, especially because, in all periods, Ancient Greek has enjoyed high prestige, and the literate borrowed heavily from it.The New Testament of the Christian Bible was also originally written in Greek. Greek was by far the most widely spoken lingua franca in the Mediterranean world, the official language of the Byzantine Empire and today the official language of Greece and Cyprus and one of the 24 official languages of the European Union.