The Greek language is a member of the Hellenic language family, a sub-group of Indo-European. The language has a long and rich history as being one of the oldest written languages in the world, and one which has influenced countless other languages globally.
Proto-Greek, also known as Proto-Hellenic is the assumed ancestor of all known Greek varients. It's somewhat difficult to reconstruct the exact boundaries between individual languages, but linguists estimate that Proto-Greek maintained unity until sometime around the Neolithic era or the Bronze Age as migrants entered the Greek peninsula. Proto-Greek is said to have been spoken predominantly around 3,000 BC, though some opinions maintain that it emerged earlier around 5,000 BC. Since Proto-Greek, the Greek language has been spoken without interruption in the Greek peninsula.
This remains the most ancient form of written Greek known to current historians. Records of Mycenaean Greek exist on the Greek mainland, Cyprus, and Crete. Tablets have been discovered around Tiryns, Thebes, Chania, Knossos, Pylos, and of course Mycenae. Most written texts are lists and inventories relating to economic and business dealings. Very little written record in the genres of poetry, mythology, philosophy, or prose narratives exist.
Mycenaean retained certain Proto-Indo-European and Proto-Greek features that didn't survive in the next phases of the language. One such feature was a set of labiovelar consonants - ɡʷ, kʷ, kʷʰ - which split into /b, p, pʰ/, /d, t, tʰ/, or /g k kʰ/ in later evolutions of the language. Another remaining feature were the semivowels of /j/ and /w/ as well as the glottal fricative /h/ between vowels. These largely disappeared in Greek as it evolved.
The Ancient Greek Language
The emergence of the Ancient Greek language is somewhat confusing. Linguists have developed theories about how Ancient Greek emerged from Mycenaean and early Greek-like speech, and while they all follow a similar narrative, these theories disagree on the details. What is known is that Ancient Greek was split into several dialects such as Doric, Attic, Ionic, Aeolic, and Arcadocypriot. Some dialects are accounted for in standard literature, but others exist in local inscriptions and writings detailing day to day life.
Additionally, a few standard historical forms of Ancient Greek are accounted for. Homeric Greek is best known for its use in the epic poems of the Iliad and Odyssey, but was also used by authors other than Homer for later poems and narratives. Homeric Greek was derived from Ionic and Aeolic dialects and differed significantly in grammar and pronunciation from other commonly spoken dialects.
Linguists have identified these various dialects of the Ancient Greek language, but agree that dialects spoken in the east differed more sharply from western dialects.
The Koine Greek Language
Koine Greek was known as the common dialect, common Attic, Hellenistic Greek, and Alexandrian Greek. Koine emerged as the common regional form of Greek spoken during the Hellenistic and Roman periods, and developed as a result of Alexander the Great's conquests in the 4th century BC. Because of the relative unification of Greek speakers, Koine Greek became a standard language used throughout the Mediterranean and Middle East during the following centuries.
Linguistically, Koine Greek shared much in common with the Attic and Ionic dialects. This was essentially the written language used Plutarch, Polybius, and is the language of the Christian New Testament and the Septuagint. Koine Greek continues to be used by the Greek Orthodox Church for liturgical services, much as Latin is used by the Roman Catholic Church.
It is interesting to note that the Septuagint's publication has led modern scholars to contend that Biblical Greek may not be a full representation of spoken Koine Greek at the time. Namely, the efforts of the original translators to follow the Hebrew and Aramaic text of the Old Testament may have influenced certain constructions and grammatical structures within the Septuagint itself.
Medieval Greek, also known as Byzantine Greek, marked the continuation of the Greek language during the Byzantine era, up to the demize of the Byzantine Empire in the 15th century. From the 7th century onwards, Greek was the only official language for government in the Byzantine Empire. The literature during this time was influenced very heavily by Koine Greek -- namely the classical and religious works published in the older language.
The translation of the Roman law into Greek and the adoption of Greek titles by emperors made Greek the official language in the Eastern Roman Empire.
The Modern Greek Language
Modern Greek, also known as Neo-Hellenic or even historically as Romaic Greek refers to the Greek language as it's spoken in the modern era. Historians mark the distinction between Medieval Greek and Modern Greek as being the fall of the Byzantine Empire in 1453, however this marks only a historical boundary and not much of a linguistic one. Many modern features of Greek developed during the so-called medieval period.
Linguists mark a few varieties of Modern Greek.
Demotic is the name used to refer to all popular varieties of Modern Greek. Demotic followed a common evolutionary path from Koine and these dialects maintain a high degree of mutual intelligibility. Demotic Greek was essentially the vernacular before the 11th century and called the "Roman" language of the Byzantine Empire. Today, a standardized version of Demotic Greek is the official language in Cyprus and Greece and is referred to as Standard Modern Greek (though less officially as Modern Greek or Demotic). This standardized version is divided into northern and southern dialects. Northern dialects include Rumelian, Epirote, Thessalian, Macedonian, and Thracian. The southern dialects are spoken in Megara, Aegina, Athens, Cyme, the Mani Peninsula, Cyprus, Constantinople/Istanbul, Crete, and several other places.
In additional to being the official language of Cyprus and Greece, Greek is a recognized minority language in parts of Italy, Albania, Syria, Armenia, Romania, Ukraine, and is used as one of the European Union's official languages. Greek speakers live in other locations throughout Europe and are a recognized ethnic minority in Hungary. Additionally, there are robust Greek communities in the United States.