Assault is, 1) an unlawful attempt, 2) coupled with a present ability, 3) to commit a violent injury on the person of another. Notice that an assault does not require a physical contact with another person, only an attempt.
An easy way to think about this is to picture someone throwing a punch, but never ultimately landing. No intent is required.
There are many forms of assault, such as assault with a deadly weapon ("ADW") and assault with great bodily injury ("GBI"). ADW and GBI can be considered a strike under the three strikes law. This is even more reason why you need an Assault Attorney to provide you with competent representation and defense.