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.

A defendant generally commits the offense of burglary of a building or habitation (1) by entering a private habitation or any part of a building that was not open to the public, (2) without the consent of the owner, and (3) with the intent to commit a felony, theft, or assault.

A defendant may also commit the offense of burglary of a building or habitation by entering with consent, but remaining hidden with the intent to commit a felony, theft, or assault—or entering with consent and attempting to commit a felony, theft, or assault, or actually committing a felony, theft, or assault.

Some states make a distinction between burglary of a habitation (a place used for overnight accommodations) and burglary of a building that is not a habitation (home). Burglary of a habitation is usually treated as a more serious offense with greater penalties.

In Maryland, burglary is defined under several degrees, with each degree reflecting the severity of the offense. First-degree burglary involves breaking and entering into someone's dwelling with the intent to commit theft or a crime of violence. This is considered a felony and carries the most severe penalties. Second-degree burglary is also a felony and involves breaking and entering into a storehouse (a structure other than a dwelling, like a garage or warehouse) with the intent to commit theft, violence, or arson. Third-degree burglary is a broader category that includes breaking and entering into someone's dwelling with the intent to commit any crime, not just theft or violence. Fourth-degree burglary encompasses breaking and entering into a dwelling or a storehouse without specifying the intent to commit a particular crime inside, or the breaking and entering with the intent to commit theft of the structure itself or its contents. Maryland law also recognizes the burglary of a motor vehicle as a separate offense. The penalties for burglary in Maryland vary depending on the degree of the offense, with more severe penalties for higher degrees of burglary, especially when the burglary involves a habitation, which is treated more seriously due to the invasion of personal living space.