Basics

To get things started off you need to know there are 2 basic types of drive for a vehicle. There is 2 wheel drive and there is 4 wheel drive. 2 wheel drive vehicles only pull the vehicle with only 2 of its 4 wheels. 4 wheel drives pull with all 4 wheels. So for simple off-roading a 2 wheel drive vehicle will do; however, if you intented to get into the sport a little more serious then i would definatly consider aquiring a 4 wheel drive vehicle. The traction is night and day differnce with a 4 wheel drive being able to go places a 2 wheel drive wouldnt even think of going. Here is a diagram from www.howstuffworks.com showing how a basic 4 wheel drive system works.

As you can see from the picture a 4 wheel drive equiped vehicle has a few extra peices. The transfer case behind the transmission would not be found on a 2 wheel drive. This is what sends the power to the front differential, which would also not be found on a 2 wheel drive, unless it was a front wheel drive car.