The language of the Greeks constituting a separate branch of the Indo-European language family, spoken primarily in Greece from the 2nd millennium BC to the present. Modern Greek dates from the 15th century and evolved from Byzantine Greek, spoken from the 5th century to the 15th century. Koine, also called Hellenistic Greek, was spoken from the 4th century BC to the 4th century AD. Ancient Greek was spoken from the 14th century BC to the 4th century BC.

It is a highly inflected language with strict rules and rather complicated grammar. The alphabet normally used is adapted from the Phoenician alphabet, circa 1000 BC.

Greek is spoken today by approximately 10 million people on the Greek peninsula and Aegean archipelago, and is the official language of Greece.