Bookmaking, like dutching, uses bets placed simultaneously on multiple selections to eliminate the unlikely outcomes and divide the locked in profit between the remaining selections. Unlike dutching, however where you are backing your selections, with bookmaking you lay the selections.
Dutching is a strategy that consists in placing back bets simultaneously in several selections. The goal is to cover as many probable outcomes as possible, while leaving out the least likely, splitting the profit equally among all the favourite selections. This strategy greatly minimises the risk associated with each bet.