Most teams quality for the World Cup by competing in qualifying tournaments based on their continental zone, while the host nation's team always qualifies automatically. The International Federation of Association Football, or FIFA, assigns each continental zone a limited number of berths for the World Cup, and teams in these zones vie for the berths.
The number of berths that FIFA assigns to each continental zone varies from tournament to tournament due to economic factors, growing populations and other variables. Five of FIFA's continental zones are Africa, Asia, Oceania, Europe and South America. North and Central America and the Caribbean all share the remaining continental zone. Only national Association Football teams recognized by FIFA are allowed to compete for World Cup berths.
Qualification tournaments typically begin two full years before the World Cup takes place. Depending on the number of entrants to the tournament during any given year, FIFA also awards one or two World Cup berths to the winners of intercontinental playoff matches. FIFA allocates 0.5 berths to continental zones competing in these intercontinental playoff matches.
For most of the World Cup's history, the previous champion's home country was also guaranteed a berth in the next tournament. However, as of the 2006 World Cup, FIFA no longer guarantees berths for defending champions.