Most vikings were self-owning farmers. There has been a long tradition of coastal peasants in Scandinavia having communaly (or corporate) owned ships. Some of the younger sons and one of the peasants of the community would sail with the cash crops (often tar, hemp, salted butter rapeseed oil, wool or charcoal) to sell and make a profit, and buy needed goods (such as salt).

The viking era started after the Franks had crushed the Frisian Kingdom and thus created a vacuum in the North Sea for traders. The Scandinavians eagerly filled that vacuum. They also discovered that coastal Britain and France was weakly defended, or in many cases not defended at all, as they could attack and be on their way before the local forces (if any) could get there by land.

As both France and England were weak and divided at the time, these raids turned into large-scale profitable extortion rackets, where the vikings would gather vast fleets with many men and demand ransom to not plunder and sack even larger cities and towns.

So, from the start, most vikings were traders sent out in ships by their friends and relatives to trade that would find a juicy target. Once word spread on the easy gains, large fleets were assembled. The majority of the men were still self-owning farmers, but by now there were mercenary vikings and trouble-makers making it their full-time profession and the hird (personal guard) of great men making a professional core of the viking host.

Towards the end of the era, the fleet was a royal expedition, with a core of the king's own hird, the hirds of his close allies and relatives and the ledung, an organisation regulated in law where self-owning farmers had to provide ships and armed and armoured men in lieu of taxes to the king.

To answer your question shortly;

• Most people were self-owning peasants and their family.

• There were outcasts among the professional vikings, who were often trouble-makers, but they were a minority. Most were respectiable people.

• There were no nobility in Scandinavia at the time, but great men looking for money and power and building a reputation as a leader of men and a warrior were not uncommon - going viking to gain power before challenging a relative or ally for the throne of a petty kingdom was not unheard of.

• Yes, the majority heading out during the height of the viking era were just Norse folk looking for a quick buck.