How many "genres" are there? I know that it's become a matter of personal definition, but I'm trying to catagorize my music collection, and have 150+ genres to choose from and this is WAY too many.

Along the same lines, If a song was considered "pop" 50 years ago, how would you catagorize it today? Would it still be considered pop, or something else? Oldies is too broad of a catagory, but so is pop.

Some food for thought, Would Frank Sinatra fit into todays definition of "POP" music? Would Britney Spears fit into the same catagory?

You might like to check out the way they have things catagorized at Billboard. They're the ones that make the music charts, and those are rather useful for figuring out what to call something.

Personally, I try not to get too complicated. You could split hairs to infinity if you were so inclined--sub-genres of sub-genres of...
I keep it pretty basic, with some subdivisions. Like, I have jazz catagorized into vocal and instrumental. But then I may divide that up a bit by era or decade. Big band gets thrown in there because it doesn't really go anywhere else but I don't have enough for its own catagory.
I tend to divide things into eras more than particular "types" because as you said something like "oldies" is too broad. Classic R&B (60s/70s), modern R&B (80s-current...I'm too old for 80s to be classic yet ).
Some artists get their own category because they are so prolific, or just deserve it--Beatles, Stevie Wonder, Led Zeppelin, Manhattan Transfer...
But basically, I guess it sort of depends on the purpose of categorizing them. Are you doing it for yourself just so you can find them? Then I would just put them into whatever genre you most identify them with. Easiest to find.
Sinatra I would put in jazz vocals simply because I don't have enough of that type to warrant a separate category. And he thought he was jazz-ish, so what the heck. You could make up your own genre--Old Crooner Guys or maybe Icons.

Well, um...that was clear as mud, eh?

Depends on your collection, too. I have so little country that I just throw it in with my world music, which is mostly Irish - hey, Johnny Cash does a great Danny Boy.

Just to finish the thought, here are the categories I have right now (alpha within):

Pop/Rock - and that does range from Rancid to Frank Sinatra
Classical
Jazz
Blues
World

OTOH, when I was younger, I did group my Pop/Rock more by affinity - well, atleast metal with metal since I had a lot of metal. Unless you really have a library - say, 1,000 CDs or more - you probably don't need to categorize a lot. YMMV.

To be honest, once I get all my CDs ripped, I might be boxing them up. Heaven knows my tapes have been boxed for seven years - and that box has not been opened. One day I'll get rid of it, but not yet.

I'm currently trying to "clean up" my library. I have well over 1000 CD's, so you can see where the genre question comes into play. I listen to EVERYTHING from contemporary Christian to Frank Sinatra, back to Bach, and through Metallica. I also have most of the "Easy Listening" guys covered (Elton John and the like). I just did a quick scan of my IPod and have over 200 genres listed, and feel this is WAY too many. Granted some of the genres are the same thing, just formatted differently (ie Rap/HipHop and HipHop/Rap) that need to be made into the same, that would still leave me with well over 100 genres. And as a Rock & Roll girl from birth, I can't bring myself to use the standard Pop/Rock genre. Rock is Rock, Pop is Pop, I can't bring the two together.

If you were catagorizing a library of well over 10,000 songs, where would you make the cut on genres? Would "Old Crooners" be a genre?

And Stu, you don't have to explain the Butthole Surfers to me, I have the album with Pepper on it; I listen to it frequently.