Difference between "tournament", "competition" and "match"

I was just reading the article about TopCoder. Before this article I thought a tournament and a competition is the same. What is the difference between tournament, competition and match?

Match is "a formal contest in which two or more persons or teams compete".

Tournament consists of multiple matches between contestants and comes from "contest between groups of knights on horseback. Modern use, in ref. to games of skill, is recorded from 1761."

Competition does not have such a problem with its meaning of "a contest for something" which is from 1610s.

Differences and relationships:
So, match is a different animal (you can not call a match neither a tournament nor competition).
Every tournament is a competition, but not every competition is a tournament.

You can also look at related term: championship.

References are from etymonline entries for match, tournament and competition.

To elaborate beyond the definitions already provided, a tournament generally refers to a specific format of competition, where competitors engage in a series of matches to determine the winner(s).

There are several types of tournaments (single elimination, double elimination, round robin, etc.), but generally speaking the goal of the tournament is to provide overall winners through a gradual sorting process based upon success within the individual tournament matches.

A competition can be any of the different types of tournaments, or it can be something less structured (such as two teams playing a single match).

First, a "match" is usually between two parties as contestant, where as a "tournament" or a "competition" is for multiple contestant.

A tournament, is a series of matches. There are generally a large number of contestants

A competition can include a tournament, or a match. It's a more general sense, and includes anything, in which there is one or more parties contesting. A competition can consist of only one contestant, which "tournament" and "matches" can't have. That's the only differences I can think up of.