Short answers, pulled from the story.
The Viking Age began on the 8th of June 793 when Norsemen attacked the holy island of Lindisfarne off the north-east coast of England. This raid involved the slaughter of monks and the dragging of treasures into the sea, an event recorded by the Northumbrian scholar Alcuin of York as a terror never before seen in Britain.
The Norse used clinker-built longships equipped with large sails and capable of 24-hour sailing to navigate both deep ocean waters and shallow river systems. This technology enabled them to sail up the Seine to Paris and the Volga to Constantinople, turning the sea into a highway rather than a barrier.
Norsemen expanded due to a combination of overpopulation, political strife, and the lure of wealthy trade networks following the unification of Norway under Harald Fairhair around 800. The political weakness of the Carolingian Empire after the death of Charlemagne in 814 made Western Europe an attractive target for raiders seeking plunder and land.
The Vikings established the Kingdom of the Isles, Orkney, York, and the Danelaw, which were ruled by Norse-Gaels and other Scandinavian settlers. In 867, the Great Heathen Army led by brothers Ivar the Boneless, Halfdan, and Ubba captured York to establish a Viking community in Jorvik.
The Varangians, often Swedes, migrated eastwards through what is now Belarus, Russia, and Ukraine to establish trade routes connecting northern Europe to the Middle East and the Byzantine Empire. They founded the settlement of Aldeigja in the 750s and established Novgorod by Rurik and his brothers Truvor and Sineus, eventually forming the Kievan Rus' state.
The Viking Age ended gradually as the Norse were assimilated into Christian kingdoms, with the Battle of Stiklestad in 1030 marking the end in Norway and the Battle of Stamford Bridge in 1066 marking the end in England. The Norse influence persisted in places like Orkney and Shetland under Norwegian rule until 1469.