What is a foul, and what happens after I call one?

A foul is non-incidental contact between opponents, meaning contact that affects continued play. Generally the player who initiates contact commits the foul, and everyone must avoid initiating contact in every way reasonably possible. Only the fouled player can call it, loudly and immediately.

Common types (section 20):

• Receiving foul: contacting an opponent while the disc is in the air and interfering with their play on it. Everyone has the right to the air space straight above their own torso (verticality).
• Throwing foul: non-incidental contact between thrower and marker. Contact with a marker's extended arms or legs is almost always on the marker.
• Blocking foul: moving solely to stop an opponent reaching the disc, or taking a position a moving player can't avoid.
• Strip: a foul that makes you lose possession.
• Force-out: an airborne receiver is knocked out-of-bounds or out of the end zone. Uncontested, they keep the disc (and a goal is awarded if they'd have landed in the end zone).

Resolution (receiving foul that affected the play):

• Uncontested: the fouled player gets the disc at the spot of the foul.
• Contested: the disc goes back to the thrower, and the stall resumes at the count reached plus one, or 6 if over 5.
• Offsetting fouls: back to the thrower, same stall rule.

Dangerous play: reckless or dangerously aggressive play (for example, colliding with a mostly stationary opponent, or contacting someone's head) is called "dangerous play" and treated as a foul. It usually needs some contact. In an observed game, an uncontested or observer-ruled dangerous play also gets a yellow card.