Life, Lust, and Silly Puns

Ok, basically there are 4 types of mountain bike suspension.
(Note: I used Imageshack because their image insertion wizard sucks. Or I probably don't know how to use it. But I think I do.)

Hardtails

A solid frame, with only a front fork as suspension.




Full suspension

A bike with both a rear shock and a front fork. The rear shock uses a pivot to transfer the motion to the shock.




Softtail

Basically a full suspension, but the rear suspension doesn't have a pivot. Generally they have less travel than pivot designs can achieve. Note the air pump looking thing near the rear wheel AND NOT THE SEATPOST MOUNTED SPRING.





What's the fourth one? Well no suspension of course. Though I don't recommend taking that bike to a technical trail. Not common, I guess cuz I couldn't find a good picture of one that looked like an actual MTB.