Thing 8: Wiki's

Ok, here's where I get a little lost.  I was browsing around, trying to get some information on Wiki's, and according to one site I looked at, "wiki" means "quick" or "easy" in Hawaiian.  I'm not sure I agree.  I get the basic concept of a wiki--but I'm confused as to how it's different from something like Google Docs.  Or is that an example of a wiki?  I am definitely interested in the wiki's developed by libraries and also those focused on 21st Century Learning.  I think the concept of the "wiki" intimidates me, though I'm sure that's silly as I probably read them all the time without even realizing it.