The Anglo-Saxons were a cultural group that inhabited much of what is now England in the Early Middle Ages, and spoke Old English. They traced their origins to settlers who came to Britain from mainland Europe in the 5th century. Although the details are not clear, their cultural identity developed out of the interaction of incoming groups of Germanic peoples, with the pre-existing Romano-British culture. Over time, most of the people of what is now southern and eastern England came to identify as Anglo-Saxon and speak Old English. Danish and Norman invasions later changed the situation significantly, but their language and political structures are the direct predecessors of the medieval Kingdom of England, and the medieval English language. Although the modern English language owes somewhat less than 26% of its words to Old English, this includes the vast majority of words used in everyday speech.

Historically, the Anglo-Saxon period denotes the period in Britain between about 450 and 1066, after their initial settlement and up until the Norman Conquest.

The history of the Anglo-Saxons is the history of a cultural identity. It developed from divergent groups in association with the people's adoption of Christianity and was integral to the founding of various kingdoms. Threatened by extended Danish Viking invasions and military occupation of eastern England, this identity was re-established; it dominated until after the Norman Conquest. Anglo-Saxon material culture can still be seen in architecture, dress styles, illuminated texts, metalwork and other art. Behind the symbolic nature of these cultural emblems, there are strong elements of tribal and lordship ties. The elite declared themselves kings who developed burhs (fortifications and fortified settlements), and identified their roles and peoples in Biblical terms. Above all, as archaeologist Helena Hamerow has observed, "local and extended kin groups remained...the essential unit of production throughout the Anglo-Saxon period." The effects persist, as a 2015 study found the genetic makeup of British populations today shows divisions of the tribal political units of the early Anglo-Saxon period.

The term Anglo-Saxon began to be used in the 8th century (in Latin and on the continent) to distinguish "Germanic" groups in Britain from those on the continent (Old Saxony and Anglia in Northern Germany). Catherine Hills summarised the views of many modern scholars in her observation that attitudes towards Anglo-Saxons, and hence the interpretation of their culture and history, have been "more contingent on contemporary political and religious theology as on any kind of evidence."