Divisions are often organised in such a way that teams or players in any given division are comparably adept at their chosen sport, such that matches are exciting. Often this is achieved by ensuring that the victors of one division are promoted to some 'higher' division upon achieving their divisional title, swapping places with the bottom-placed team in that higher league. Variations on this idea exist in the form of playoffs.
A league is such a set of divisions (or can describe an individual division within a league) in which teams can move between differently ranked divisions.
In soccer, each nation has its own football league.