Here is a comprehensive summary of the Wikipedia article on championships:

A championship is a competition designed to determine the ultimate champion, and sports utilize several distinct systems to do so. In the title match system, a top contender must defeat the reigning champion, a format common in combat sports like boxing and MMA, while tournament systems use knockout brackets, as seen at Wimbledon or the European Football Championship. Many sports employ a league system with a round-robin schedule (e.g., soccer, rugby), but North American leagues like the NFL and NBA use a hybrid playoff system, combining a regular season with a knockout tournament that culminates in events like the Super Bowl and NBA Finals. Interestingly, in the NFL, the "Championship Games" are actually conference semi-finals that determine Super Bowl participants—a naming quirk from when the AFC and NFC were separate leagues. Season systems, used in motorsports like Formula 1, award points across multiple races, crowning the driver with the most points at year's end as champion. Finally, some competitions blend formats, such as Jeopardy!'s Tournament of Champions, which combines title match regular play with an end-of-season knockout tournament.