In the law of tort, property, and criminal law a trespasser is a person who commits the act of trespassing on a property, that is, without the permission of the owner. Being present on land as a trespasser thereto creates liability in the trespasser, so long as the trespass is intentional. At the same time, the status of a visitor as a trespasser (as opposed to an invitee or a licensee) defines the legal rights of the visitor if they are injured due to the negligence of the property owner.

A licensee can mean the holder of a license or, in U.S. tort law, a licensee is a person who is on the property of another, despite the fact that the property is not open to the general public, because the owner of the property has allowed the licensee to enter. The status of a visitor as a licensee (as opposed to a trespasser or an invitee) defines the legal rights of the visitor if they are injured due to the negligence of the property possessor (not necessarily the owner).

In the law of torts, an invitee is a person who is invited to land by the possessor of the land as a member of the public or one who enters the land of another for the purpose of business dealings with the possessor of the land. The status of a visitor as an invitee (as opposed to a trespasser or a licensee) defines the legal rights of the visitor if they are injured due to the negligence of the property owner.

The attractive nuisance doctrine applies to the law of torts in some jurisdictions. It states that a landowner may be held liable for injuries to children trespassing on the land if the injury is caused by an object on the land that is likely to attract children. The doctrine is designed to protect children who are unable to appreciate the risk posed by the object, by imposing a liability on the landowner. The doctrine has been applied to hold landowners liable for injuries caused by abandoned cars, piles of lumber or sand, trampolines, and swimming pools. However, it can be applied to virtually anything on the property of the landowner.

There is no set cutoff point that defines youth. The courts will evaluate each "child" on a case-by-case basis to see if the "child" qualifies as a youth. If it is determined that the child was able to understand and appreciate the hazard, the doctrine of attractive nuisance will not likely apply.

Under the old common law, the plaintiff (either the child, or a parent suing on the child's behalf) had to show that it was the hazardous condition itself which lured the child onto the landowner's property. However, most jurisdictions have statutorily altered this condition, and now require only that the injury was foreseeable by the landowner.

Alan Gallay, "Walter Ralegh: Architect of Empire" (Basic Books, 2019)