Competition is a contest between individuals, groups, nations, animals, etc. for territory, a niche, or allocation of resources. It arises whenever two or more parties strive for a goal which cannot be shared. Competition occurs naturally between living organisms which co-exist in the same environment. For example, animals compete over water supplies, food, and mates, etc. Humans compete for water, food, and mates, though when these needs are met deep rivalries often arise over the pursuit of wealth, prestige, and fame. Business is often associated with competition as most companies are in competition with at least one other firm over the same group of customers.

Competition may give incentives for self-improvement. For example, if two watchmakers are competing for business, they will hopefully improve their products and service to increase sales. If one watchmaker is more responsive to the needs of consumers, this watchmaker will flourish. If birds compete for a limited water supply during a drought, the more suited birds will survive to reproduce and improve the population.

Rivals will often refer to their competitors as "the competition". The term can also be used to refer to the contest or tournament itself.