The Swedish language does not use the apostrophe. At all.
Colour me surprised when I finally figure out how to use the finicky thing while browsing IRC rooms,
(after driving at least six operators and several anal retentive spellers nuts with improper usage).
Anyways, to keep it on topic. Traps can be categorized in two columns, automatic, and manual.
Automatic traps trigger once, or several times (until jammed with bits of victims(or out of ammo)), in this category we find the cage-traps, the stone fall traps and of course the weapon traps.
Manual traps are a little more complicated in that they don't trigger the moment someone steps into one. It could be anything from the simple spike trap to the impressive flooding chamber. Or even something sinister like the collapsing roof. These traps needs to be triggered manually, either by dwarf operated lever, or pressure plates (Even I haven't managed to figure out how to best use those, and I'm insane.) which can be triggered by water, hostiles, or your own citizens for humorous effects. These traps can be used to alter passages, trigger spikes, toggle bars and grates or floodgates and even doors and hatches. For some more indirect mayhem. Heck, you could make a giant catapult using a bridge. The possibilities are plenty!
Unless of course you're up against Kobolds, for that I recommend relocating the fortress. Cheeky little Commando wannabes...