At full strength, each rugby union team has 15 players on the field.
The 15 players are divided into eight forwards and seven backs. Forwards generally contest possession in scrums, lineouts, rucks, and mauls, while backs are typically organized to exploit space and create attacking opportunities. The positions have distinct roles, although modern rugby requires players throughout the team to run, pass, tackle, and support play.
The forwards wear numbers 1 through 8, and the backs normally wear numbers 9 through 15. The traditional numbering system helps identify positions, even though squad numbering in some competitions can vary.
Rugby sevens is a related format played with seven players per team and shorter matches. Rugby league also uses 13 players per side. Those formats are common sources of confusion, but the full traditional rugby union format is played with 15 players per team.