In Japan, it seems there are 3 popular flavors of karate. The flavor I practice is Japanese Karate (日本空手協会; nihonkaratekyoukai), sometimes called JKA. It's a variation of Shotokan Karate. Kyokushin Karate is the third popular karate style, and it is quite different from JKA and Shotokan. My club has 3 tests a year, and each test has three parts: kihon (fundamentals), kumite (sparring), and kata (forms). Kihon is simply fundamental techniques — we demonstrate various kicks, punches, and blocks with no opponent. Kumite is sparring. For beginners, the moves are determined ahead of time. For example, Person A will try to punch Person B in the head, and Person B simply has to block it and counter. High level sparring is free sparring (自由組手; jiyuukumite), where you can attack and block as you like. This is the same as at tournaments. The third part of a karate test is a kata. A kata is a 30-60 second routine that one memorizes in advance.
Karate tournaments are much like karate tests. There are two categories, kumite and kata. Men only fight men, women only fight women, kids only fight kids their own age, and for adults there are no age classes. There are no weight classes, there are no skill classes, opponents are chosen randomly, and it's single elimination. There are categories for individuals and teams (3 people per team). In Akita, there are only two tournaments a year: the All-Akita Tournament, and the All-Tohoku Tournament.
Our rank starts at 10 kyuu, white belt, and we work our way down to 3 kyuu, brown belt. After about 3 years, if things go well, one can obtain a black belt, and become 初段 (shodan) — literally, first degree black belt. After first degree black belt is second degree black belt, and so on. Adults don't use yellow, green, or purple belts — we just go from white to brown. Anyhow, different branches of different martial arts all have their own color scheme.
Here are some karate pictures from 2009. I earned the kyuu certificates up in Akita. The photos are from the adult national tournament at the Tokyo Municipal Gymnasium in Tokyo.