Exacty, as keyb_gr states.
ID3 tags: http://en.wikipedia.org/wiki/Id3_tag. You also can do a search using the search box at the upper left–lots of information here in past posts.
As a general matter, the Clip (like an iPod) displays music, audiobook and podcast file information based on the files’ ID3 tags. ID3 tags are data in the music, podcast or audiobook files that provide information about the file, often the file’s title, album/book name, author, year, and genre. Audiobooks and music files you buy often have the ID3 tags information already there and filled in; other times, and when you rip the computer files yourself from a CD, you need to add the information into the computer files yourself–it is a simple fill-in-the-blank process. CD “rippers” often will connect up to Internet databases and add the information in for you, as part of the ripping process; you also can add the information using a tag “editor” such as MP3Tag and The Godfather (both freeware available on the Internet) or use Windows to do so (right click on the file, choose Properties, and then go to the Details tab on Vista or choose Advanced on XP).
The Clip makes it one step easier for audiobook and podcast files: if files or folders of files are placed in the Clip’s Audiobooks or Podcasts folders, or if the genre ID3 tags for a file is either Audiobook or Podcast, and if the file’s ID3 tags are not otherwise filled in, the Clip will use the file’s file and folder names for organization and display purposes.
And so your choices are: fill in/correct your files’ ID3 tags using a tag editor or Windows, or put the files in the Clip’s Audiobooks or Podcasts folders and have the Clip use the files’ file and folder names.
Hopes this makes it a bit clearer–