Team size, uniforms, numbers, and what the captain can ask the referee
A team is two players. Only those two, the ones written on the score sheet, can play. One of them is the captain, and the score sheet says who that is.
Both players are on the court the whole time. There is no substitution and no libero. If one player cannot keep playing, the team is incomplete and loses the set or the match. How that score is finished is in Playing Format.
For FIVB, World, and Official competitions, players cannot get outside help or coaching during the match. Age-group events, and phases 1 and 2 of the Continental Cup, are the exceptions written into the rule.
The basic uniform is shorts or a bathing suit. A jersey or tank top is optional unless the tournament rules require one. A hat or other head covering is allowed.
For FIVB, World, and Official competitions, teammates wear the same color and style, and the uniform has to be clean.
Players play barefoot unless the first referee allows otherwise.
If both teams show up in the same color, the referee tosses to decide which team changes.
The first referee can also allow:
The two players are numbered 1 and 2.
The number goes on the chest. If a player is allowed to play without a shirt, it goes on the front of the shorts. It has to contrast with the fabric, be at least 10 cm tall, and the stroke of the number has to be at least 1.5 cm wide.
Anything that could injure someone, or that gives a player an artificial advantage, is forbidden.
Glasses and contact lenses are allowed. The player wears them at their own risk.
Compression pads and other padded protection are allowed for support or to protect an injury. For FIVB, World, and Official senior competitions, those pads and any visible underwear have to match a color in the uniform. Black, white, or a neutral color is also allowed, as long as every player wearing them wears the same color.
The captain is responsible for the team's conduct.
Before the match, the captain signs the score sheet and represents the team at the toss.
During the match, only the captain talks to the referees, and only while the ball is out of play. The captain can do three things:
At the end of the match, both players thank the referees and the other team. The captain signs the score sheet to confirm the result.
If a protest was started during the match and never resolved, the captain can confirm it as a written protest on the score sheet at the end.