Umpires

Decisions about play are made by umpires, which are indicated by use of hand signals. The number of umpires on a given game can range from a minimum of one to a maximum of seven.

• 1 plate umpire
• Up to 3 base umpires
• Up to a further 3 umpires positioned in the outfield

Official umpires are often nicknamed "blue", because of their uniforms: navy slacks, a powder blue shirt and a navy baseball cap. However, many umpires now wear navy blue, red, white or black shirts, and many associations require their umpires to wear grey slacks instead. All umpires in the same game must wear matching uniforms.