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 New Hampshire, burglary is defined under RSA 635:1 as entering a building or occupied structure, or separately secured or occupied section thereof, with the purpose to commit a crime therein, without the consent of the person in lawful possession. The state distinguishes between different types of burglary based on the circumstances of the unlawful entry. Burglary is a felony in New Hampshire, and the severity of the charge can be influenced by factors such as whether the building is a dwelling, whether the burglary occurred at night, and whether the perpetrator was armed with a deadly weapon. Burglary of a dwelling is considered more serious and carries harsher penalties than burglary of other types of structures. Additionally, New Hampshire law recognizes 'criminal trespass' as a separate but related offense, which involves unauthorized entry without the specific intent to commit a further crime. The penalties for burglary can include imprisonment, fines, and restitution, and are designed to reflect the seriousness of the offense and the potential harm to victims.