Old English developed from a set of Anglo-Frisian or Ingvaeonic dialects originally spoken by Germanic tribes traditionally known as the Angles, Saxons and Jutes. As the Anglo-Saxons became dominant in England, their language replaced the languages of Roman Britain: Common Brittonic, a Celtic language, and Latin, brought to Britain by Roman invasion. Old English had four main dialects, associated with particular Anglo-Saxon kingdoms: Mercian, Northumbrian, Kentish and West Saxon. It was West Saxon that formed the basis for the literary standard of the later Old English period, although the dominant forms of Middle and Modern English would develop mainly from Mercian. The speech of eastern and northern parts of England was subject to strong Old Norse influence due to Scandinavian rule and settlement beginning in the 9th century.
Old English is one of the West Germanic languages, and its closest relatives are Old Frisian and Old Saxon. Like other old Germanic languages, it is very different from Modern English and difficult for Modern English speakers to understand without study. Old English grammar is quite similar to that of modern German: nouns, adjectives, pronouns and verbs have many inflectional endings and forms, and word order is much freer. The oldest Old English inscriptions were written using a runic system, but from about the 9th century this was replaced by a version of the Latin alphabet.
Englisc, which the term English is derived from, means 'pertaining to the Angles'. In Old English, this word was derived from Angles (one of the Germanic tribes who conquered parts of Great Britain in the 5th century). During the 9th century, all invading Germanic tribes were referred to as Englisc. It has been hypothesised that the Angles acquired their name because their land on the coast of Jutland (now mainland Denmark) resembled a fishhook. Proto-Germanic *anguz also had the meaning of 'narrow', referring to the shallow waters near the coast. That word ultimately goes back to Proto-Indo-European *h₂enǵʰ-, also meaning 'narrow'.
Another theory is that the derivation of 'narrow' is the more likely connection to angling (as in fishing), which itself stems from a PIE root meaning bend, angle. The semantic link is the fishing hook, which is curved or bent at an angle. In any case, the Angles may have been called such because they were a fishing people or were originally descended from such, and therefore England would mean 'land of the fishermen', and English would be 'the fishermen's language'.
Old English was not static, and its usage covered a period of 700 years, from the Anglo-Saxon settlement of Britain in the 5th century to the late 11th century, some time after the Norman invasion. While indicating that the establishment of dates is an arbitrary process, Albert Baugh dates Old English from 450 to 1150, a period of full inflections, a synthetic language. Perhaps around 85 per cent of Old English words are no longer in use, but those that survived are basic elements of Modern English vocabulary.