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.

In Pennsylvania, assault is categorized into two main types: simple assault and aggravated assault. Simple assault is generally defined as attempting to cause or intentionally, knowingly, or recklessly causing bodily injury to another; negligently causing bodily injury to another with a deadly weapon; or attempting by physical menace to put another in fear of imminent serious bodily injury. Simple assault is typically a misdemeanor, but it can be a felony under certain circumstances, such as an assault against a child under 12 by an adult 21 or older. Aggravated assault, a more serious offense, involves causing or attempting to cause serious bodily injury to another, or causing injury with a deadly weapon under circumstances manifesting extreme indifference to the value of human life. Aggravated assault is usually a felony. The concept of assault in Pennsylvania aligns with the general definition where the apprehension or fear of harm is sufficient for the crime to be committed, even without physical contact, which would escalate the crime to battery. However, it's important to note that Pennsylvania law does not have a separate statute for battery, and actions that would constitute battery in other jurisdictions are typically prosecuted as assault in Pennsylvania.