Libero is an Italian word meaning "free," a measure of the player's ability to enter and exit the game without smashing the team's substitution limit. Before the Libero rule, coaches would rotate their defensive specialists in and out of the game. This player can serve for one person and cannot play in the front row nor attack. The person does not count as a substitution also. Simply, they are known as a permanent back row specialists. They are probably the best passers or diggers in the team. They can serve, but cannot jump to spike. Also they usually wear a different color uniform from the rest of the team.
There are 6 positions for Libero in each volleyball team. Each of these players takes one of the six positions, including three front-row positions and three back-row positions. The Libero player can only enter the game when in a back-row position. When the rotation forces the Libero player to move to the front-row position, another player will enter the game to replace his place.
The purpose of keeping a Libero player in a baseball game is to pass the ball over the net. If there is a bad pass, the setter needs to work harder to get to the ball and most likely the set will be off target causing the hitter to adjust to the ball. As a Libero, the player needs to be an aggressive passer and wants to get to every ball putting up good passes to the target, so the rest of his team can do their job, making the Libero the most important position on the court.
The libero is actually a new concept in volleyball. It has been introduced to the international arena in 1998. The NCAA officially recognized the libero and adapted its rules in 2002. Traditionally the NCAA followed the FIVB's ruling by adopting the Libero for the men's game in 1999 and the women's game in 2002.
It is very easy to identify the Libero player in the team because they wear a different colored jersey. So it will help you to distinguish between a Libero and the rest of the players in the team. For example, if a team's colors are yellow and green, the libero will wear yellow while the rest of the team is dressed in green.
Unlike other players, a libero can be substituted into a game as many times as a coach wants. A team may make unlimited replacements involving the Libero. At least one rally must be played between libero substitutions, and the switch can only be made before the referee blows his whistle and while the ball is out of bounds. Teams can only make Libero replacements while the ball remains out of play and before the referee blows the whistle for the serve.