A lot of people suffer with knee problems. The knee is one of the most fragile parts of the body because it has to take on so much of the body's weight. It's constantly moving, bending and absorbing shock.
The knee is made up of two joints called the tibiofemoral articulation and the patellofemoral coupling (check this out - the knee is the largest joint in the body!), with some shock absorbing cartilage in between. Since the knee depends so much on the muscles and ligaments around it to help it survive, sprains and tears of these muscles or ligaments can be a problem causing knee pain. It's pretty obvious when this is the case, as you can typically feel a wrenched or torn area in the knee the moment it happens.
If you get a sprain, one of the best things you can do is rest your knee. Get off it as much as possible and ice it as much as possible. Reducing the swelling in a knee injury can help eliminate a lot of the pain. If you don't, you'll feel that injury every time you move a muscle in your leg. You should also put your knee up, on a soft pillow or whatever, to elevate it. This will take additional pressure off your knee, making it less painful. Finally, if you compress the injury with a wrap - like an Ace bandage - you should feel better, too. In fact, when you're kneeing around post injury, wear your Ace bandage to prevent further strains and pains and injuries. Look, no one like an injury. No one knee -ds it.