The crime of assault varies from state to state (and under federal law), but is generally defined as intentionally putting another person in reasonable apprehension or fear of an imminent (immediate) harmful or offensive contact. The crime of assault may be committed even if there is no physical contact, as the criminal physical contact constitutes the separate crime of battery.

The crime of assault with a deadly weapon (also known as aggravated assault) occurs when someone uses a deadly weapon (gun, knife, club, tire iron, brass knuckles, etc.) during an assault.

In California, assault is defined under California Penal Code Section 240 as an unlawful attempt, coupled with a present ability, to commit a violent injury on the person of another. It is important to note that actual physical contact is not necessary for an assault charge; the key element is the attempt or threat to cause harm. Assault with a deadly weapon, classified as aggravated assault, is addressed under California Penal Code Section 245(a)(1). This occurs when an individual assaults another with a deadly weapon or instrument other than a firearm, or by any means likely to produce great bodily injury. The term 'deadly weapon' is broadly interpreted and can include objects that are not inherently deadly but can be used in a way that might cause serious injury or death. The penalties for assault with a deadly weapon are significantly higher than for simple assault and can result in a felony charge, with potential state prison time, depending on the circumstances of the offense and the defendant's criminal history.