Gout is one of the many kind of arthritis and occurs only when the crystals made of uric acid accumulates between the joints causing extreme pain. Uric acid is a chemical which is filtered by the kidney to be out of the blood which normally doesn't bring any harm.
Gout happens when the body is producing too much acid or due to the fact that the body doesn't eliminate well enough. Amount of uric acid in the body is increased by some foods that contain the chemical purine.
Purine is break down in the kidney and becomes uric acid which will eventually be eliminated by the body through urine or sweat. Foods that are high in purine is normally not encouraged for people who have gout or have a high risk of getting it.