Greek is one of the Indo-European languages and by far the largest and most prominent member of the Hellenic languages. As of 2012 it was estimated to have 13.4 million speakers, largely in Greece, but also in Cyprus and throughout the world because of the Greek diaspora. According to the 2016 census, there are just under a quarter of a million (237,000) Aus­tra­lians who speak Greek at home.

Greek is attested in writing from at least 3,500 years ago, making it the Indo-European language with the longest recorded history of all. There is a significant pre-Greek substrate whereby approx. 1,000 words were borrowed into a very early stage of Greek from the languages that were spoken in the peninsula before Indo-Europeans arrived there. In antiquity, Ancient Greek was one of the most significant and prestigious languages of the age; Latin, for example, adopted a swathe of words, particularly those to do with scientific or intellectual concepts, from the language. It continued in prominence as the lingua franca of the eastern Roman Empire (later known as the Byzantine Empire). Even after the Ottoman conquest, Greek speakers remained widely distributed across this area, particularly in modern-day Turkey and the Egyptian city of Alexandria. After the 1923 population exchange between Greece and Turkey, the vast majority of Greek speakers in the Old World came to be living in Greece or Cyprus.

The different periods of the Greek language are known as such:

  • Proto-Greek: not recorded, but the hypothetical ancestor of all Hellenic languages
  • Mycenaean Greek: attested from the 15th century BCE onwards
  • Ancient Greek: with various dialects (Attic, Ionian, Doric) this was the version spoken during the height of Greek civilisation in antiquity
  • Koine Greek: marked by the fusion of the Attic and Ionian dialects; sometimes known as “Biblical Greek” as much of the New Testament is written in it
  • Mediaeval Greek: also known as Byzantine Greek, as it was the language of the Byzantine Empire
  • Modern Greek: the form of the language spoken from the end of the Byzantine Empire up till today