A film leader is a length of film attached to the head or tail of a film to assist in threading a projector or telecine. A leader attached to the beginning of a reel is sometimes known as a head leader, or simply head, and a leader attached to the end of a reel known as a tail leader or foot leader, or simply tail or foot.
The Academy leader was introduced on 1 November 1930 by the Academy of Motion Picture Arts and Sciences. It has numbers marked once every foot (16 frames per foot in 35 mm film), counting down from 12 to 3. "NINE" and "SIX" are spelled out, to avoid confusion between 6 and 9 when viewed upside-down. The numbers are printed upside down relative to the visual program so as to be right side up when the projectionist is threading a projector. At 3, a quick beep is heard (but this beep is muted on 35mm theatrical release prints to prevent it from being accidentally played in the theater). The Academy leader is specified by SMPTE 301. The standard also specifies the position and placement of the cue marks at the end of the reel.