Burglary is generally the unlawful entry of a building or structure to commit a felony criminal offense (crime), theft, or assault. The definition of burglary varies from state to state (and in the federal system), and some states have different degrees of severity of the burglary offense—depending on the nature of the unlawful entry (type of building or structure), the intended purpose, and the illegal action taken by the defendant once inside the building or structure. In some states, breaking into an automobile, a coin-operated machine, or an ATM (automated teller machine) with the intent to commit a theft may also constitute the crime of burglary.

In Pennsylvania, burglary is defined under Title 18 § 3502 of the Pennsylvania Consolidated Statutes. The crime of burglary involves entering a building or occupied structure with the intent to commit a crime therein, unless the premises are open to the public or the defendant is licensed or privileged to enter. It is important to note that the intended crime does not need to be theft; it can be any felony or certain misdemeanors. Pennsylvania law distinguishes between burglary of a residential building, which is considered a felony of the first degree, and burglary of a structure that is not adapted for overnight accommodation, which is a felony of the second degree, provided no one is present. If the building or structure is not adapted for overnight accommodation and no one is present, the offense may be graded lower. The state does not require actual breaking and entering; mere unlawful entry with criminal intent suffices. Additionally, Pennsylvania law recognizes criminal trespass as a separate offense, which may be charged when a person enters a property without authorization but without the intent to commit an additional crime.