Trespassing is when someone enters physical property, not his or her own, without permission. It could be a parking lot, a business, or somebody’s yard. If that person does not have permission to go there, or has not been given implicit permission because of the type of business (a fast food place, for example) the person is trespassing. If the person is told they are trespassing and is asked to leave, if they refuse to leave, that person can be arrested for trespassing.