What's the sharingan? Sharingan is one of Kakashi's strongest jutsus. It is nicknamed the "copy wheel eye" because with it, you can copy your opponent and make him believe you can read his mind or the future. Actually, it is just a simple trick.

It is basically an eye technique consisting of hypnotism and attention for details. Combining those two elements, you can go from copying the body, to the mind, to the jutsu, scaring the hell out of your enemy.

Method:


1. Copy the movements of the rival.

2. Once the enemy is confused, guessing what he is thinking is very easy.

3. When the opponent is completely freaked, with hypnotic gen-jutsu you suggest what seal he should perform.

4. The enemy is even more panicked and you beat him up.
Look at the following comic strip for graphic info.

The enemy is freaked out by Kakashi using his Sharingan to copy his technique.

Now Kakashi copies his enemy, Zabuza's words. As he is able to say it at exactly the same time as Zabuza, Zabuza gets even more freaked out.

Zabuza's veins are popping out!

Now Kakashi uses his Sharingan to hypnotise Zabuza.

Yeah! Enemy got beaten to a pulp! All the above info came from this great site, http://www.uber-sushi.net/kakashi/kakashi.html