The International Biology Olympiad (IBO) is a biological olympiad for pre-university students under the age 20, and is one of the most well-known International Science Olympiads. The first IBO was held in Czechoslovakia in 1990, and it has since been held annually. The competition have gradually expanded to include more than 75 countries participating countries across five continents. All participating countries send the four winners of their National Biology Olympiad to the IBO, usually accompanied by two adults who are members of the international jury for the duration of the competition.