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 Colorado, burglary is defined under state statutes and is classified into different degrees based on the circumstances of the offense. Colorado recognizes three degrees of burglary. First-degree burglary (CRS 18-4-202) is the most serious and involves the unlawful entry into, or remaining in, a building or occupied structure with the intent to commit a crime therein, usually involving assault or menacing. Second-degree burglary (CRS 18-4-203) involves similar unlawful entry or remaining with the intent to commit a crime, but without the elements of assault or menacing that elevate it to first-degree. Third-degree burglary (CRS 18-4-204) is generally related to breaking into safes, vaults, or other secure repositories to commit theft. Burglary of a dwelling is typically treated more severely than burglary of other structures. Additionally, Colorado law also recognizes the offense of possession of burglary tools (CRS 18-4-205), which is a separate crime. Penalties for burglary offenses in Colorado vary depending on the degree of the burglary, with first-degree burglary carrying the most severe penalties, including potential prison time.