they store info about pages you visit to load them faster. some people dont like them cause they store info on where you visit, i dont like them cause they are a pain. look through them. most can be deleted. DONT delete any subscription one though (i.e. ar15.com, hotmail, yahoomail, ect.....)you can limit the space allowed for temp internet files, it is in internet options, then settings, turn it to lower than 60 meg.