What exactly is tendinitis?

I am a swimmer and i just recently found out that I have tendinitis... Can anyone help exlplain to me what exactly that is?

A tendon is the end part of a muscle that attaches the muscle to the bone. The normally very elastic and soft muscle tapers off at the end to form the much more dense and stiff tendon. While this density makes the tendons stronger, the lack of elasticity of the tendon and the constant pulling on its attachment to the bone with movement, makes it much more susceptible to a low level of tearing at a microscopic level. This tearing will produce the inflammation and irritation known as tendinitis. Often spelled tendonitis, either spelling is correct for this condition. Tendinitis is usually seen after excessive repetitive movement with which the tendon gradually becomes tighter until the fibers start to tear. For example, a person who plays tennis may over- use the muscles of the elbow through hitting the ball repetitively and cause tendonitis to the area.

it is a inflamation of your tendons ( kind of string which help you to move your body)

Inflammation of the tendon, resulting from overuse, undertraining, poor technique and various other reasons. Best treatment is REST, ice and take an anti-inflammatory.

Sorry,using my cell phone to help(as I always do)so I don't really have time to research it more.I have to play 2-4min guitar solos extremly fast,so I always take time to condition my fingers/hands before I play.