P4P can stand for:

Pound for pound

Pound-for-pound is the term used in boxing, mixed martial arts and other combat sports to describe a fighter's value in relation to fighters of different weight classes.

Pay for placement

An abbreviation of the term Pay for Placement or "Pay for Performance". The concept was invented at Overture (now Yahoo! Search Marketing) and later adopted by their competitors, most famously Google's AdWords. Under the model advertisers bid on the rights to present a search result for a specific search terms in an open auction. When someone enters a search term that has been bid on, the results from the auction on that search term are presented, ranked from highest bid to lowest. It is also referred to as Pay per click advertising.

When this idea was first introduced, there was a lot of controversy. Many felt that the results would be irrelevant, but the auction model has proven to be quite effective at producing relevant results for searches where one wants to buy something . P4P is now seen as the most efficient and effective way to monetize search engines .

P4P is also a UK based clothing re-sale company.

P4P is also being used within the healthcare industry as a model to reward healthcare providers who have better outcomes than those who do not.

Overture filed a lawsuit against Google in 2002 claiming AdWords infringed its patent on this mechanism. It was settled in 2005 with Google issuing stock to Yahoo! in return for a perpetual license. (See Yahoo! Search Marketing.)