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 Missouri, burglary is defined under Missouri Revised Statutes Section 569.160 and 569.170. Burglary in the first degree involves entering or remaining unlawfully in a building or inhabitable structure for the purpose of committing a crime therein, with the additional element that the person is armed with explosives or a deadly weapon, or causes or threatens immediate physical injury to any person who is not a participant in the crime, or if the person has entered an inhabited dwelling. Burglary in the second degree is a class D felony and covers situations where an individual unlawfully enters a building or inhabitable structure with the intent to commit a crime inside, but without the aggravating factors that elevate the crime to first-degree burglary. Missouri law also recognizes the crime of 'Possession of Burglary Tools' under Section 569.180, which makes it illegal to possess any tool with the intent to use it in a burglary. The state does not specifically categorize the burglary of an automobile, coin-operated machine, or ATM as burglary, but such acts may fall under different statutes related to theft or property damage.