While the basic quest, contract, and mission structure are all very well planned out and obvious, there is another type of event that is more off-the-cuff called Random Encounters.
These are not really quests but just what they sound like - random encounters in which you do something specific right then, on the spot.
These are indicated on the map by gold "!" signs and come in a number of generic types, including the following:
Set-Upon Encounter -- a random group of thugs set upon you. This can be triggered by simply walking near enough to them for it to flag, or you can be lured in by a young child to be attacked.
Church-Insult -- one of the random preachers will insult you in front of a crowd of peasants - and you have the option of defending yourself verbally.
Challenge Encounters -- A challenge by an odd tyro fighter that comes in three or four encounters, each of which he loses.
The purpose for these Random Encounters is just to provide a mix of comic-relief and some free XP... It is a good idea not to avoid them then...