What are the rules for UFC?

[JJ]

what are the differences in the rules for UFC and other fighting. i know that in some you cant kick in the head or elbow when on the ground. you cant hit in the back of the head, or bite . can you break or twist small joints.

[JesseF]

Fouls in the UFC:

Butting with the head.
Eye gouging of any kind.
Biting.
Hair pulling.
Fish hooking.
Groin attacks of any kind.
Putting a finger into any orifice or into any cut or laceration on an opponent. (see Gouging)
Small joint manipulation.
Striking to the spine or the back of the head. (see Rabbit punch)
Striking downward using the point of the elbow. (see Elbow (strike))
Throat strikes of any kind, including, without limitation, grabbing the trachea.
Clawing, pinching or twisting the flesh.
Grabbing the clavicle.
Kicking the head of a grounded opponent.
Kneeing the head of a grounded opponent.
Stomping a grounded opponent.
Kicking to the kidney with the heel.
Spiking an opponent to the canvas on his head or neck. (see piledriver)
Throwing an opponent out of the ring or fenced area.
Holding the shorts or gloves of an opponent.
Spitting at an opponent.
Engaging in unsportsmanlike conduct that causes an injury to an opponent.
Holding the ropes or the fence.
Using abusive language in the ring or fenced area.
Attacking an opponent on or during the break.
Attacking an opponent who is under the care of the referee.
Attacking an opponent after the bell (horn) has sounded the end of a round.
Flagrantly disregarding the instructions of the referee.
Timidity, including, without limitation, avoiding contact with an opponent, intentionally or consistently dropping the mouthpiece or faking an injury.
Interference by the corner.
Throwing in the towel during competition.

[fmbrecords1]

1. no knees or kicks to a grounded opponent.
2. no biting
3. no eye gouging
4. No low-blows
5. No punching directly to the back of the head
6. No small joint manipulation
7. No pulling hair

[TaoJ]

You actually can kick or knee a grounded opponent - but only to body/legs. NOT to the head.