This is a bit embarrassing, please bear with me because I know nothing about this stuff. I want to buy an old vintage record player and a bunch of records, but I'm looking on ebay and it states whether the records are 33 or 45 or 78 RPM. I have no idea what this means, and how do I know which are compatible with a record player? Are they all compatible? Is one of the RPM better than another? Please help me out, thanks!!