By the 16th cent. B.C., Greek-speaking people were established in Greece, probably having come as invaders from the north. In antiquity there were a number of dialects of the Greek language, the most important of which were Aeolic, Arcadian, Attic, Cyprian, Doric, and Ionic. Ancient Greek was prevalent in the Balkan peninsula, the Greek islands, W Asia Minor, S Italy, and Sicily. Because of the political and cultural importance of Athens in the classical period of Greek history, the Athenian dialect, Attic, became dominant. From Attic there developed an idiom called the koiné, which means "common" or "common to all the people" and which became a standard form of Ancient Greek.
After Alexander the Great the koiné developed into an international language that remained current in the central and E Mediterranean regions and in parts of Asia Minor and Africa for many centuries. Most of the New Testament was written in the koiné, which helped to gain a wide audience for Christianity. Byzantine Greek, based on the koiné, was the language of the Byzantine or East Roman Empire, which lasted from A.D. 395 until it was crushed by the Turks in 1453.
The earliest surviving texts in Ancient Greek are of the 15th cent. B.C. and are written in a script known as Linear B, which was deciphered in 1953 by Michael Ventris. Later documents, including inscriptions and literary works, are written in the Greek alphabet, which was derived from the script of the Phoenicians c.9th cent. B.C. A variety of the Greek alphabet is still used today for the Greek language.
Modern Greek stems directly from the Attic koiné and dates from the fall of the Byzantine Empire in 1453. The official language of Greece and one of the official languages of Cyprus, Modern Greek is spoken today by about 12 million people, chiefly in Greece and the Greek islands (10 million speakers), Turkey (600,000), Cyprus (550,000), and the United States (390,000). The Greek language has not changed much in its long history. The differences are largely in pronunciation and vocabulary, but they also include divergences in grammar. Modern Greek, for example, has absorbed a number of loan words from Turkish and Italian, although its vocabulary is essentially that of Ancient Greek.
The spoken form of Modern Greek, however, differed markedly from the written form until recently. The latter, referred to as katharevousa, was used by the government, the schools, and the mass media until the mid-1970s and is much more like Ancient Greek than the spoken form, which is called démotiké. Démotiké, the language of popular speech, has more foreign loan words and a simpler grammar than katharevousa. Although a literature in démotiké developed during the 20th cent., it was not until 1976 that it was accepted as the official written Greek language (see Greek literature, modern).
Both the nouns and verbs of Ancient Greek were highly inflected. Verbs had active, middle, and passive voices; indicative, subjunctive, optative, and imperative moods; singular, dual, and plural numbers; and many tenses. Nouns had three genders (masculine, feminine, and neuter) and five cases (nominative, genitive, dative, accusative, and vocative). Unlike Latin, Greek had a word for the definite article. Three accent marks are used in Greek, the acute (´), the grave (̀), and the circumflex (ˆ). In Ancient Greek they denoted a pitch accent related to the length of vowels, but in Modern Greek they serve as a stress accent. A symbol known as a rough breathing over an initial vowel represented the h sound in Ancient Greek, while the symbol for a smooth breathing over an initial vowel made clear the absence of aspiration. Though still retained today, the breathing marks no longer indicate pronunciation. In punctuation, the semicolon (;) stands for the question mark, and a raised dot denotes the semicolon and colon.
See P. S. Costas, An Outline of the History of the Greek Language (1936); E. H. Sturtevant, The Pronunciation of Greek and Latin (2d ed. 1940); O. Eleftheriades, Modern Greek: A Contemporary Grammar (1985).