Old English (Ænglisc, Anglisc, Englisc) or Anglo-Saxon is an early form of the English language that was spoken and written by the Anglo-Saxons and their descendants in parts of what are now England and southern and eastern Scotland, more specifically in the England Old Period, between at least the mid-5th century and the mid-12th century. What survives through writing represents primarily the literary register of Anglo-Saxon.

It is a West Germanic language closely related to Old Frisian. Old English had a grammar similar in many ways to Classical Latin, and was much closer to modern German and Icelandic than modern English in most respects, including its grammar. It was fully inflected with five grammatical cases (nominative, accusative, genitive, dative, and instrumental), two grammatical numbers (singular and plural) and three grammatical genders (masculine, feminine, and neuter). First and second person personal pronouns also had dual forms for referring to groups of two people, in addition to the usual singular and plural forms. The instrumental case was somewhat rare and occurred only in the masculine and neuter singular; it could typically be replaced by the dative. Adjectives, pronouns and (sometimes) participles agreed with their antecedent nouns in case, number and gender. Finite verbs agreed with their subject in person and number.

English is a West Germanic language spoken originally in England, and is now the most widely used language in the world. It is spoken as a first language by a majority of the inhabitants of several nations, including the United Kingdom, the United States, Canada, Australia, Ireland and New Zealand. It is the third most common native language in the world, after Mandarin Chinese and Spanish, and the most commonly used as a second language; its total number of speakers – counting both native and non-native – exceeds those of any other language. English is an official language of the European Union, many Commonwealth countries and United Nations, as well as in many world organisations.

English arose in the Anglo-Saxon kingdoms of England and what is now south-east Scotland, but was then under the control of the kingdom of Northumbria. Following the extensive influence of Great Britain and the United Kingdom from the 18th century, via the British Empire, and of the United States since the mid-20th century, it has been widely dispersed around the world, becoming the leading language of international discourse and the lingua franca in many regions.