They were like web directories and the stuff they link to, but for one person's interests. The closest comparison in modern terms is a personal blog, but these would often host music and videos and random niche stuff like game save files and code.
They often had a MIDI file auto-play if you had a sound card with MIDI support. Fancier sites had an MP3, but not every computer could handle it. Some had guestbooks or forums.
Everything/nothing was usually abbreviated to e/n, but that leads to even fewer results on Google.
