An important part to the game from an official's perspective is the signals. This is a primary method of communicating with players, coaches, scorekeepers, and fellow officials. Without signals, simply blowing a whistle would not always be a good indicator of what action the official has just noticed. Proper use of mechanics is important to accurately demonstrate what action has just occurred. As a new official develops, signals are often one of the hardest habits to pick up on as it is not an intuitive reaction but rather a learned trait of the game. In developing this part of an official's mechanics, it is important that the signals are crisp and clean as to denote confidence and knowledge in each call.
For the majority of basketball's existent, officiating a game has generally been a two person task. However, as the game has developed over the years it has been recognized that it is more effective for officials to work in groups of three know as a 3-person crew. The reason for this is primarily to provide a better officiated game. This allows officials to provide better court coverage by having an additional position. With that, it allows for officials to get angles on plays which in turn provides a higher success rate in accuracy of calls. The remainder of this tutorial will focus on the game in terms of a 3-person crew.
The positions in a 3-person crew are the "lead", "center" (also sometimes referred to as "Slot"), and "trail". The lead is a position on the baseline when the ball is in the frontcourt. The center is the position generally at free-throw line extended in a front court setting. They are also noticeable by being the only official on one half of the court known as the "weak side". Lastly the trail is the official generally closest to half court and is located on the same side of the court as the lead. This is known as the "strong side" and is commonly the location of the ball in addition to two officials. As the ball changes possession and subsequently transitions from one end of the court to the other, the center official retains the same position. However, the trail official will transition to lead and the formerly lead official will transition to trail.
While these positions commonly hold the same status throughout live ball play, there are methods of replacing other officials positions on the court. During the course of a live ball, the lead official may initiate what is known as a "rotation". To rotate, the lead official will cross the baseline from the strong side to the weak side as the ball rotates across the court. This now becomes the new strong side and requires the center official to become the trail. Likewise, the formerly trail official now fills into the center position on weak side. The reason for doing this is that the strong side commonly has more players, more competitive matches, and a higher percentage of calls to be made. By having two officials, it allows for these officials to see plays from a better angle and cover more plays.
During a dead ball such as a violation or foul, you will often see officials move about the court into new positions. This method of chaning positions is known as switching. Given a certain scenario as to where a violation occurs or who is the calling official determines the method in which the officials will switch. However, before putting the ball next in play it is imperative that the inbounding official is not the center. This is because the side of the court in which the ball is to be inbounded is the strong side and thus requires to officials for coverage. The following chart depicts a basic coverage area as well as positioning in a frontcourt setting.