Koine Greek is part of the legacy left by Alexander the Great's imperial conquests which spread from Asia Minor, Egypt, the Near East, and as far as India. Though his death saw the end of the cast empire he had forged, Koine Greek, or common Greek continued to be spoken in the lands he conquered and served as the ancestor of Modern Greek.

The Greek language, as we know it today, had its origin during the classical era, though it has undergone a considerable number of changes. In our day, in its modern form, demotikí or 'popular' Greek is the official language of Greece and Cyprus. It is also recognized as a minority language in Italy, Turkey, and Albania.

Greek is part of the Indo-European family of languages. The earliest form of Greek is thought to have originated in the 14th century BCE in Cretan inscriptions. Mycenaean Greek is distinguished from later Classical or Greek of the 8th century BCE and after, when texts came to be written in the Greek alphabet.

Various theories about the origins of the Greek language exist. One suggests that it originated with a migration of proto-Greek speakers into Greece, which is dated to any period between 3200 BC to 1900 BC. Another theory holds that Greek evolved in Greece itself out of an early language of Indo-European origin.

The Greek language including Attic and Modern Greek, is written in a non-Latin script. Greek is one of the richest surviving languages in the world today, with a vocabulary more than 600,000 words. Some scholars have stressed the similarity of Modern Greek to millennia old Greek languages. The extent of Modern Greek's commonality with ancient Greek is the subject of debate. It is claimed that a "reasonably well educated" speaker of the modern tongue can read the ancient dialects, but it is not made very clear how much of that education consists of exposure to vocabulary and grammar obsolete in normal communication.

The Greek language spoken in both in the Hellenistic and Byzantine eras is nearer to Modern Greek. From 1934 to 1976 there was an attempt to impose a purified language, an attempt to correct centuries of natural linguistic changes) as the only acceptable form of Greek in Greece.

After 1976, Dimoti'ci or the "speech of the people" was accepted by the Greek government as the defacto form of the language. A large number of words and expressions have remained unchanged down through the centuries, and have made their way into a number of other languages, including Latin, Italian, German, French and English. Some examples of these include mostly terminology names, such as astronomy, philosophy, democracy and anthropology.