A simple bidding strategy in which the amount you pay depends on whether an end-user clicks on an ad. The amount can be a fixed amount (such as $1.00) or a percentage based on the room rate. The amount is multiplied by the number of nights in the booking.
This bidding strategy is called "Max" CPC because you define the maximum that you are willing to pay in the auction. You're often charged less -- sometimes much less -- than your maximum cost-per-click (max. CPC) bid, which is the most you'll typically be charged for a click
For more information, see Setting Max CPC Bids.