I see a whole bunch of tags on some of the books  that I've been searching, some that look like user names with TBR or WL added after, some with just a date, others that make no sense at all.  Can anyone tell me what those are?  I thought those were just to be used to help you search for things, or to help categorize a book.

Thanks!!

Those are personal tags. If you go to the Help Center and read about tags, personal Tags are fine as long as they are not attempting to describe the condition of a book or reserve it or anything.

A lot of those RL and TBR tags are for games. 

I just joined a game yesterday taht requires the players to tag some of their  TBR books so others can look and we can steal eachothers TBRS from each other because we want one of the books.

Like Melanie said they are allowed as long as they aren't books descriptions like "unpostable" or "no dust jacket". 

Thank you all for the explanation!  I'm always impressed by the knowledge of the people on these boards, and the speed of responses!