Lay Betting explained

To lay an outcome is to accept someone else's back bet: you win their stake if the outcome fails, you pay out at the odds if it lands. Your liability on a lay at 4.00 is three times the backer's stake — the asymmetry newcomers underestimate.

Laying completes the toolbox: three-way football markets can be attacked from either side ('this favourite is too short' becomes actionable without picking who beats them), and hedging a position becomes a matter of laying what you earlier backed.