A prefetcher is like a helper that helps your computer know what you might want to see or use next. It looks at what you have already looked at or used and gets ready to show you more things like that so that they load faster. It's kind of like how you might already have your toys out to play with before you even ask for them because your mom or dad knows what you like to play with. The prefetcher just helps your computer do the same thing with information on the internet or on your computer so that you don't have to wait so long for it to load.