What is Feudalism? A simple definition?

Feudalism is a political and military system between a feudal aristocrat (a lord or liege), and his vals. In its most clic sense, feudalism refers to the Medieval European political system composed of a set of reciprocal legal and military obligations among the warrior nobility, revolving around the three key concepts of lords, vals, and fiefs. Although derived from the Latin word feodum (fief), then in use, the term feudalism and the system it describes were not conceived of as a formal political system by the people living in the Medieval Period.