Regarding the number of competing nations, Fed Cup is considered as the largest women's team sports competition which is held annually.
Fed Cup is the tennis competition for women representing their respective countries. It is equivalent to the Davis Cup, conducted for men. To celebrate the Golden Jubilee of the International Tennis Federation in 1963, the Fed Cup was established. In the inaugural year, there were teams from 16 countries which took part in the competition. There was no prize money for the competition at that time. By 1994, the number of competitors extended up to 73, and reached 107 in 2017.
Total 16 best nations teams are assigned in two World Groups: I and II, the first being for elites.
World Group play-offs are held in which the winning teams cemented their place for the following year and proceed to the next levels to qualify for the finals whereas the four losing teams compete in another play-off with the winning teams of the World Group II. This is conducted to decide the relegation and promotion of the teams.
Below the level of World Groups, nations are assigned to three regions: Americas, Asia/ Oceania and Europe/Africa. The first two regions have two groups whereas the third regional group has three teams.
In zonal competitions, teams compete in round-robin format.
The winning teams of the first and second regional group and the top two teams of the third regional group progress to the World Group II play-off.