Decorative or Display:
This is everything else. Script fonts, calligraphic (handwriting) fonts, ornate fonts, goofy fonts, what have you. Rage Italic is a decorative font:

As is Gilligan's Island, even though it's very different from Rage Italic:

Top Font Crimes

1. Using fonts together that are too alike. It's not bad to use more than one font together. Just make sure they're different.

2. Using Comic Sans. It's just wrong. Don't do it.

3. Liberal use of display fonts. Use them only in the right situations. And don't use contrasting ones together (i.e., fancy script font with silly font). And never use them for a large body of text, unless you intend to annoy your reader (or unless it's a "mild" decorative font).