Question

how did vikings affect european society?

Answer 1

All I know about vikings is that they were pirates and raided european countries. So I would guess the economy was not so great because people's stuff were being taken. So they couldn't make a lot of money (to an extent). then they couldnt buy things (to an extent). Something like that

Answer 2

Greatly accelerated the development of feudal structures and the transition away from the Roman model of citizenship. The repeated Viking incursions into Europe in the mid first millenium put a very high premium on local security, that is, for people to be certain that there existed a strong local highly-responsive defensive force. As the power of the Empire receded, it no longer became possible to depend on far-away legions, on the frontier, keeping the barbarians far away. You needed armed men right there, in the neighborhood.

This led ordinary people to pledge their fief to some local lord, who could supply a castle and weaponry. In return for pledging their loyalty to the lord, they received guaranteed protection. Meanwhile, the uselessness of Rome gave rise to widespread tax evasion. The result is a collapse of the Roman model, where citizens pay taxes to Rome, Rome pays legiosn to guard the frontier, and there is less direct relationship between rich and poor locally. In its place we have the feudal model, where there is essentially no relationship between local people and distant central authority, particularly Rome, and instead a very strong tie between wealthy and poor locally, which is the feudal lord-tenant relationship.