While you can certainly ride a mountain bike on paved surfaces, you really can't take a road bike off the pavement. Mountain bikes are perfect for any riding being done off of paved surfaces. This includes muddy or rocky singletrack trails, dirt roads, gravel paths, and other rugged terrains.

Suspension may be referred to as short or long travel: Short-travel suspension (less than 120mm) suspension provides all-round riding performance with an emphasis on smooth trails and going uphill. Long-travel suspension (greater than 120mm) is best for descending rough terrain at high speeds with greater control.

On mountain bikes travel can range from 80mm on an xc bike to 200mm on a big downhill speed machine. Less travel usually means a bike is more efficient on the climbs and the suspension doesn't suck up the pedal power as much.