Generally, prize money or purse is a monetary prize awarded for winning or coming a place in a competition. Prize money also has a distinct meaning in naval warfare; it was a monetary reward paid out to the crew of a ship for capturing an enemy vessel.

In the 16th and 17th centuries, captured ships were legally Crown property. In order to reward and encourage sailors' zeal at no cost to the Crown, it became customary to pass on all or part of a captured ship's value to the capturing captain for distribution to his crew. (Similarly, all belligerents of the period issued Letters of Marque and Reprisal to civilian privateers, authorizing them to make war on enemy shipping; as payment, the privateer sold off the captured booty.)

This practice was formalized via the Cruizers and Convoys Act of 1708. An Admiralty Prize Court was established to evaluate claims and condemn prizes, and the scheme of division of the money was specified. This system, with minor changes, lasted throughout the colonial, Revolutionary, and Napoleonic wars.

If the prize were an enemy merchantman, the prize money came from the sale of both ship and cargo. If it were a warship, and repairable, usually the Crown bought it at a fair price; additionally, the Crown added "head money" of 5 pounds per enemy sailor aboard the captured warship. Prizes were keenly sought, for the value of a captured ship was often such that a crew could make a year's pay for a few hours' fighting. Hence boarding and hand-to-hand fighting remained common long after naval cannons developed the ability to sink the enemy from afar.