Trespass is the unauthorized entry upon the land (real property) of another. Trespass may occur when one enters—or causes something to enter—another's property without permission. The law has traditionally recognized a claim or cause of action for damages based on trespass.

The owner of real property generally has the right to exclude all others from use of the property—although this right to exclude others may be relinquished in limited circumstances, such as when there is an easement allowing another to use the property. As a general rule, any unauthorized entry upon land of another is a trespass even when there is no damage or only slight damage.

Thus, to prove a trespass claim, the plaintiff must show that it owned the property or had a right to exclude others from the property. Some courts have recognized that the right to explore for oil and minerals is a valuable property right that can be legally protected through a trespass claim.

To recover damages for trespass to real property, a plaintiff must prove that: (1) the plaintiff owned or had a lawful right to possess real property; (2) the defendant entered the plaintiff’s land and the entry was physical, intentional, and voluntary; and (3) the defendant’s trespass caused injury to the plaintiff’s right of possession.

The only relevant intent is that of the actor (defendant) to enter the property. The actor’s subjective intent or awareness of the property’s ownership is irrelevant.

In Florida, trespass refers to the unauthorized entry onto another person's land without permission. The law in Florida recognizes trespass as a legal wrong, and property owners have the right to exclude others from their land. To establish a trespass claim in Florida, the plaintiff must demonstrate ownership or the right to possess the property, show that the defendant intentionally and physically entered the property, and prove that the trespass caused harm to the plaintiff's possessory rights. It is important to note that the defendant's intent to enter the property is what matters, not their knowledge or awareness of the property's ownership. Florida Statutes Title XLVI Chapter 810 specifically addresses trespass and outlines the penalties for various forms of trespass, including trespass on property other than structures or conveyances (Section 810.09), trespass on school grounds (Section 810.097), and trespass on agricultural land (Section 810.11). Penalties can range from a second-degree misdemeanor to a third-degree felony, depending on the circumstances of the trespass.