Self-defense is a set of awareness, assertiveness, verbal confrontation skills, safety strategies, and physical techniques that enable someone to successfully escape, resist, and survive violent attacks. A good self-defense course provides psychological awareness and verbal skills, not just physical training. 

 The right of self-defense (also called, when it applies to the defense of another, alter ego defense, defense of others, defense of a third person) is the right for people to use reasonable force or defensive force, for the purpose of defending one's own life (self-defense) or the lives of others, including –in certain ... 

What is an assault-An assault is the act of inflicting physical harm or unwanted physical contact upon a person or, in some specific legal definitions, a threat or attempt to commit such an action. It is both a crime and a tort and, therefore, may result in either criminal and/or civil liability. Wikipedia 

 Battery is the intentional and offensive or harmful contact with another person. ...Battery is when the threat (assault) is carried out and the person is harmed in some way. Criminal battery and civil battery may be the same or differ slightly depending on jurisdiction. 

 The main difference between a battery charge and an assault charge is the actual presence of harm and the threat of harm. Someone can only be charged with battery if they have caused real physical harm to someone, while a person can be charged with assault if the mere threat of harm is present.