A Vassal simply put is a person who either resides within their lands (mostly inbetween events) and or works for that lord directly. Beyond that simple explanation the rest is very much an in game thing because every lord is different and the jobs they wish done are thus different.
I get ya. Thanks, I'll find out the details in game.
Still technically an out of game consideration: Does one HAVE to be a vassal of a particular land? Is it the same as being a citizen?
Like for example, my character is theoretically just "passing through". Does she have to declare an allegiance of some sort, or can she exist forever as a traveler?