International cricket
Most games are played as parts of "tours", when one nation travels to another for a number of weeks or months, and plays a number of matches of various sorts against the host nation. The ICC also organises competitions that are for several countries at once, including the Cricket World Cup & ICC T20 World Cup.
Test cricket
Test cricket is the longest form of the sport of cricket and is considered its highest standard. Test matches are played between national representative teams with "Test status", as determined and conferred by the International Cricket Council (ICC). The two teams of 11 players each play a four-innings match, which may last up to five days (or longer in some historical cases). It is generally considered the most complete examination of teams' playing ability and endurance. The name "Test" stems from the long, gruelling match being both mentally and physically testing.