A rugby league team has a maximum of 13 players on the field. This is one of the main differences between rugby league and rugby union, which fields 15 players per side.
The 13-player structure developed after the Northern Rugby Football Union reduced the number of players from 15 to 13 in 1906. The change created more open space and encouraged a faster style of play.
Teams also use substitutes, and modern professional competitions generally allow an interchange bench. However, substitutions do not change the normal on-field maximum: each side still has 13 players during ordinary play.
The positions are commonly grouped into six forwards and seven backs. Numbering conventions vary slightly by competition, but the traditional squad numbers run from 1 to 13 for the starting team.