Vikings were Scandinavian seafaring warriors who raided the coasts of Scandinavia, Europe and the British Isles from the 9th century to the 11th century. Vikings should not be confused with Northmen or Scandinavians in general during the Viking Age.
Before the Norse sagas were written in the 13th century, Vikings were known from two historical approved sources. Widsith does not specify the meaning of "viking", but stated they were regarded as a kin, not belonging to other groups named, such as Swedes, Geats, south-Danes, Wends and Werns. Adam of Bremen clearly translated the "term viking" to nothing other than pirates (See sources below).
After the viking attacks on the English shores, the victims referred to those Vikings as ethnic groups rather than as those performing a "profession". Hence, the term "Vikings" got mixed with the term Northmen, and referred to all Scandinavians, and not pirates in particular.
King Harald I of Norway finally was forced to make an expedition to the west to clear the islands and Scottish mainland of Vikings. Numbers of them fled to Iceland, but the Norse sagas are rather subjective in their descriptions, and hence the Vikings in those sagas are sometimes characterized as heroes, later shaping the attitude against Vikings during the 18th century Romantic period. Still, in Scandinavia, no Viking was part of the society described together with other accepted professions. It may even be possible that Vikings were outlaws – several sources name Vikings in association with Jomsborg/Julin, which, according to modern history, was a refugee center for Slavic pirates, as opposed to the descriptions in the Norse saga.