What is a kink and is it different from fetish?

Kink is a set of pleasurable activities that people choose to do together that in other contexts are not pleasurable or usual. Often Kink is associated with BDSM and with Fetishes. The main difference between kink and fetish is that when one has a fetish one normally cannot get aroused without the fetish present, whereas a kink adds sexual pleasure but is not necessarily always needed for pleasure to be achieved.