In sport, doping is the use of a drug that athletes or competitors are not allowed to use. Certain drugs, such as steroids, are not allowed (or banned) in professional sports. This is because they can help a competitor's performance, by making them stronger or faster. This gives them an unfair advantage over other competitors. The drugs may be legal, but competitors will not be allowed to use them. Many sports make competitors take a drug test to prove that they are not using any drugs.