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Finders, keepers is an English adage with the premise that when something is unowned or abandoned, whoever finds it first can claim it. This idiom relates to an ancient Roman law of similar meaning and has been expressed in various ways over the centuries. Of particular difficulty is how best to define when exactly something is unowned or abandoned, which can lead to legal or ethical disputes.
- One of the most common uses of "Finders, Keepers" involves shipwrecks. Under international maritime law, for shipwrecks of a certain age, the original owner may have lost all claim to the cargo. Anyone who finds the wreck can then file a salvage claim on it and place a lien on the vessel, and subsequently mount a salvage operation.
- Philosophies that advocate a right to own land and other natural resources often appeal to the doctrine of finders keepers in the case of claiming ownership of what was previously unowned (see Terra nullius).
- In the United States, the Homestead Act allowed people to claim land as their own as long as it was originally unowned and the property was then developed by the claimant.
- In the field of social simulation, Rosaria Conte and Cristiano Castelfranchi have used "finders, keepers" as a case study for simulating the evolution of norms in simple societies.
The children's rhyme upon discovering a lost object is "Finders, keepers; Losers, weepers".
- Parker v British Airways Board 
- Lost, mislaid, and abandoned property
- Adverse possession ("possession is nine-tenths of the law")
- Uti possidetis
- Theft by finding
- "Finders, keepers | Define Finders, keepers at Dictionary.com". Dictionary.reference.com. Retrieved 2013-05-11.
- Nicole J. Saam and Andreas Harrer: Simulating Norms, Social Inequality, and Functional Change in Artificial Societies