what tag format does iTunes use?

I'm still uploading my library. I've gotten to my compilation albums. These are old. Like, 15 years old. The track reads album/song name/artist/year. When I import these the title stays the same; iTunes isn't sorting the information into its different fields. Since Sony's Walkman did, I'm guessing that the tags that iTunes can read is different.

I did a search for tag converters and found a whole bunch of stuff but I'm apprehensive about downloading something without knowing its reputation. Can someone suggest a tag converter or at the very least tell me which tag to convert to (so I make a better formed decision).

Thanks,
sws