Most Test, One-Day and Twenty20 matches take place in the form of "tours". In a tour, one nation travels to another and plays warm-up matches, which may be first-class matches, against domestic teams such as county or state teams, a series of Test matches against the host nation, and either a series of One-Day (ODi) and T20 matches against the host nation or a tournament involving the host nation and another touring nation. Tours may include Test, ODI and T20I matches, or just one or two of these formats.