Here is a couple links to get you started http://musclemedia.com/training/hiit.asp well crap I only have that one haha. But here is how HIIT works if you don't want to read the arcticle, which you should! Basically it goes on the basis that your body tries its best to conserve calories when running low intensity, aka not sprinting. It also is not that hard on your body so you can recover easier afterworks since you are using your aerobic system( oxygen) vs your anaerobic(without oxygen). You will be doing any form of cardio you wish, but running is easiest. But you can swim, bike, whatever. You start off small, only 4 minutes a session, which may sound crazy! Wtf how can I burn fat and calories doing 4 minutes? yeah fuck off. But no, HIIT is the best way to burn the most calories. You will start off jogging for 30 seconds, then you will sprint 90% for 30 seconds, jog 30, sprint 30, etc. The you slowly build this up. By sprinting your body is forced to burn calories since it is trying to maximize them rather than conserve them when you jog. This is also very hard on the body and your body will burn calories for many hours later recovering. It also will increase your explosiveness and work your leg muscles out at the same time! So if you are trying to lose fat and stalling, or like me you HATE running long distances, then HIIT might be right for you!