What is a libero in volleyball?

• A team may name up to two liberos on the score sheet. Only one may be on court at a time.
• The libero's uniform must have a different dominant colour from the rest of the team.
• The libero may replace any player in a back-row position.

What the libero may not do:

• Serve.
• Block or attempt to block.
• Complete an attack hit from anywhere if, at contact, the ball is wholly above the top of the net.
• Set an attacker with an overhand finger pass from inside the front zone: a teammate may not then attack that ball while it is wholly above the net. The same pass from behind the front zone is free.

Libero replacements:

• Unlimited, and not counted among the six substitutions.
• There must be a completed rally between two replacements.
• Made while the ball is out of play and before the whistle for service, through the libero replacement zone.
• The libero can be replaced only by the player they came on for, or by the second libero.
• When rotation would take the libero to the front row, they go off and the replaced player returns.

If a libero is injured, ill, expelled or disqualified, or the coach declares them unable to play, a team with no other libero may re-designate any player not on court as the new libero for the rest of the match. The original libero may then not play again in the match.

The position gives smaller, quicker players a specialist role and lengthens rallies by strengthening defence. The different shirt lets the referees see at a glance that the limits are being kept.