Unfair competition in a sense means that the competitors compete on unequal terms, because favourable or disadvantageous conditions are applied to some competitors but not to others; or that the actions of some competitors actively harm the position of others with respect to their ability to compete on equal and fair terms. It contrasts with fair competition, in which the same rules and conditions are applied to all participants, and the competitive action of some does not harm the ability of others to compete. Often, unfair competition means that the gains of some participants are conditional on the losses of others, when the gains are made in ways which are illegitimate or unjust.
Principles of fair competition To an important extent, the principles of fair competition in the business world are defined by law, and therefore unfair competition may well be unlawful or criminal. But because the forms of competition can change continually and new forms of competition may arise, competition may be unfair, but not illegal, at least not until a legal rule is explicitly made to prohibit it. The exact meaning of unfair advantage or harm caused in business competition may be vague or in dispute, in particular if different competitors promote different interpretations which suit their own interests. It may be difficult to define what it would mean to compete on equal terms, and the operative terms of competition that exist in reality may be challenged only when a participant is seriously disadvantaged by them. Often "equal terms" is defined as an "equal opportunity" or "equal chance" to compete.
• Sport
Unfair competition may occur in games if a participant in some way deviates from the rules of the game, or has privileged access to important information or resources that should in principle be available to all participants in the game, or none of them. Participation in the game normally assumes that participants have an equal ability