I know this is going to sound like a daft question, but what does Long File name support mean?

Does it mean that if a player does not support it, it will not play the CDR / DVD+R if the files have more than 8.3 as a file name format or does it mean it just displays the first 8 characters on the menu?

In other words, am I going to have to rename all my mp3's before I put them on a disk to get it to work?

Thanks