The history of English is conventionally, if perhaps too neatly, divided into three periods usually called Old English (or Anglo-Saxon), Middle English, and Modern English. The earliest period begins with the migration of certain Germanic tribes from the continent to Britain in the fifth century A.D., though no records of their language survive from before the seventh century, and it continues until the end of the eleventh century or a bit later. By that time Latin, Old Norse (the language of the Viking invaders), and especially the Anglo-Norman French of the dominant class after the Norman Conquest in 1066 had begun to have a substantial impact on the lexicon, and the well-developed inflectional system that typifies the grammar of Old English had begun to break down.

The period of Middle English extends roughly from the twelfth century through the fifteenth. The influence of French (and Latin, often by way of French) upon the lexicon continued throughout this period, the loss of some inflections and the reduction of others (often to a final unstressed vowel spelled -e) accelerated, and many changes took place within the phonological and grammatical systems of the language.

The period of Modern English extends from the sixteenth century to our own day. The early part of this period saw the completion of a revolution in the phonology of English that had begun in late Middle English and that effectively redistributed the occurrence of the vowel phonemes to something approximating their present pattern.

Other important early developments include the stabilizing effect on spelling of the printing press and the beginning of the direct influence of Latin and, to a lesser extent, Greek on the lexicon. Later, as English came into contact with other cultures around the world and distinctive dialects of English developed in the many areas which Britain had colonized, numerous other languages made small but interesting contributions to our word-stock.

The historical aspect of English really encompasses more than the three stages of development just under consideration. English has what might be called a prehistory as well. As we have seen, our language did not simply spring into existence; it was brought from the Continent by Germanic tribes who had no form of writing and hence left no records. Philologists know that they must have spoken a dialect of a language that can be called West Germanic and that other dialects of this unknown language must have included the ancestors of such languages as German, Dutch, Low German, and Frisian. They know this because of certain systematic similarities which these languages share with each other but do not share with, say, Danish. However, they have had somehow to reconstruct what that language was like in its lexicon, phonology, grammar, and semantics as best they can through sophisticated techniques of comparison developed chiefly during the last century.

Similarly, because ancient and modern languages like Old Norse and Gothic or Icelandic and Norwegian have points in common with Old English and Old High German or Dutch and English that they do not share with French or Russian, it is clear that there was an earlier unrecorded language that can be called simply Germanic and that must be reconstructed in the same way. Still earlier, Germanic was just a dialect (the ancestors of Greek, Latin, and Sanskrit were three other such dialects) of a language conventionally designated Indo-European, and thus English is just one relatively young member of an ancient family of languages whose descendants cover a fair portion of the globe.