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 Maine, burglary is defined under Title 17-A, §401 of the Maine Criminal Code as the intentional entry into a place with the purpose to commit a crime therein, without the consent of the person who has the right to withhold consent. Burglary is considered more serious if it involves a dwelling place, which is any structure that is intended for overnight accommodation of persons. The severity of the offense and the penalties can vary based on factors such as whether the burglary was committed at night, if a dangerous weapon was used, or if the offender has prior convictions. Maine law distinguishes between burglary of a dwelling place (residential burglary) and burglary of other structures (non-residential burglary), with residential burglary generally carrying harsher penalties. Additionally, Maine law recognizes the offense of burglary of a motor vehicle under Title 17-A, §405. The intent to commit a crime is a crucial element of burglary, and the intended crime typically includes felony, theft, or assault. Penalties for burglary can range from fines to imprisonment, and the degree of the charge (e.g., Class A, B, or C crime) will influence the severity of the punishment.