From The Art and Popular Culture Encyclopedia
Assertiveness is a trait taught by many personal development experts and psychotherapists and the subject of many popular self-help books. It is linked to self-esteem and considered an important communication skill.
As a communication style and strategy, assertiveness is distinguished from aggression and passivity. How people deal with personal boundaries; their own and those of other people, helps to distinguish between these three concepts. Passive communicators do not defend their own personal boundaries and thus allow aggressive people to harm or otherwise unduly influence them. They are also typically not likely to risk trying to influence anyone else. Aggressive people do not respect the personal boundaries of others and thus are liable to harm others while trying to influence them. A person communicates assertively by not being afraid to speak his or her mind or trying to influence others, but doing so in a way that respects the personal boundaries of others. They are also willing to defend themselves against aggressive incursions.