The tennis scoring system is a standard widespread method for scoring tennis matches, including pick-up games. Some tennis matches are played as part of a tournament, which may have various categories, such as singles and doubles. The great majority are organised as a single-elimination tournament, with competitors being eliminated after a single loss, and the overall winner being the last competitor without a loss. Optimally, such tournaments have a number of competitors equal to a power of two in order to fully fill out a single elimination bracket. In many professional and top-level amateur events, the brackets are seeded according to a recognised ranking system, in order to keep the best players in the field from facing each other until as late in the tournament as possible; additionally, if byes are necessary because of a less-than-full bracket, those byes in the first round are usually given to the highest-seeded competitors.