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 Washington State, burglary is defined under RCW 9A.52. Burglary offenses are categorized into different degrees based on the severity and circumstances of the crime. First-degree burglary (RCW 9A.52.020) is the most serious, involving entry into a building with the intent to commit a crime against a person or property, and it is armed with a deadly weapon or assaults someone. Second-degree burglary (RCW 9A.52.030) involves similar unlawful entry with criminal intent but without the aggravating factors of the first degree. Residential burglary (RCW 9A.52.025) specifically pertains to unlawful entry into a dwelling with intent to commit a crime, distinguishing it from other buildings. Burglary in the second degree is a class B felony, while residential burglary and burglary in the first degree are class A felonies, with the latter carrying more severe penalties. Additionally, Washington recognizes burglary of a vehicle if it is used for human lodging (RCW 9A.52.095), and this is treated as a class C felony. The state does not require physical breaking and entering; simply entering with the intent to commit a felony, theft, or assault suffices for the crime to be charged.