What exactly is gout?

A type of arthritis. Caused from uric acid crystals accumulating in a joint. Any condition that causes high amounts of uric acid to circulate in blood stream may cause this. The body is either producing too much or not excreting through kidneys fast enough. An attack is usually very painful and can cause redness and swelling at the affected joint. Certain foods and medications can precipitate an attack.
See below. It is a form of arthritis that can leave deposits if uris acid crystals in the joint, creating swelling, pain and heat.
Arthritis. Gout is a condition caused by excess uric acid in the soft tissues and joints. Uric acid is a metabolic waste product disposed of mostly by the kidneys and to a lesser extent by the gut. Over production or slow elimination leads to uric acid accumulation. In the joints it causes attacks of swelling and pain. In soft tissue it causes chalky depositis called tophi. Kidney stones are also possible.
Inflammed crystals. Gout is caused by excess storage of uric acid. If if gets too concentrated (>6 in blood tests) it forms crystals that the body can "notice" and this triggers redness, swelling and pain mainly in/around joints. This is gout, and it starts in about 5% of people with a uric acid of 9 (per year). Recurrent gout flares cause joint damage which can cause persistent pain.