What are the starting commands, and how do standing and crouch starts work?

Before the start: the Starter makes sure the timing system and judges are ready.

Races run entirely in lanes (for example 100m, 200m, 400m, hurdles): the commands are "On your marks", "Set", then the gun. On "On your marks" athletes approach the starting line, on "Set" they take up their starting position, and when all are steady again the Starter fires.

Races not run entirely in lanes (for example 1500m): the commands are "On your marks" and then the gun, once all athletes are steady in their starting position.

• Once "On your marks" has been given, late athletes cannot join the event.
• No part of an athlete's body may be on the ground on or over the starting line when "on their marks".
• If the Starter has to speak to an athlete after "On your marks", the athletes stand up and the Starter's Assistant places them on the assembly line again.
• Standing start: allowed for all track events. No part of the hand or knee may touch the ground.
• Crouch start: only in races run entirely in lanes. Both hands must touch the ground. At "On your marks" one knee is on the ground, and at "Set" the knee is raised.
• Starting blocks: Under 11 and above only, for races up to 400m including first relay legs.
• For athletes with a hearing impairment the Starter may use a flag, strobe light or other visual device as well as the pistol.