Whereas a battery requires an actual touching, an assault only requires the threat of the offensive touching of another person. It is not illegal to raise one's arm with the hand in a fist. However, if the act is preceded by circumstances that would cause another person to believe reasonably that he/she is in danger of being injured, then an assault has been committed. As long as there is an overt act and the victim believes attack is imminent, then assault is committed, even if someone prevents the assailant from attacking or the assailant decides not to attack. For example:
Assume that I verbally threatened to cut you with a knife and I reach into my pocket just as I step toward you. Although you cannot readily determine if I have a knife you are legally permitted to defend yourself on the assumption that I do have a knife, since my actions would convince any reasonable person that I have a knife and I intend to commit bodily injury. Even if I am bluffing, you have acted justifiably if you defend yourself.
The state may charge a person with either an assault or a battery. However, since an assault must logically precede a battery, many states call a battery an "assault and battery."
Just as in the old children's saying, "Sticks and stones may break my bones, but words will never hurt me," mere words, no matter how offensive, usually do not constitute an attack to which you may physically defend yourself. A few states do permit defense against offensive words if they are used against a woman.