Reading wikipedia's disambiguation page about the "rank" word I see many concept of rank of many different matematical object.
I only know about the rank of a graded poset and the rank of a set that tell us its position in the Von Neumann hierarcy. In these two cases the "rank" concept give us a value of one element in relation to the other elements or help us to order them in hierarchies or classify them in some way.
Is this always true? There is a general definition/concept of rank in mathematics? What have in common all these rank concepts and what are the differences?