To be assertive is to assert or express your rights, to stand up for yourself and your values and beliefs, and to be able to express your true feelings openly. It is to be able to declare yourself, who you are, what you think and feel. It is an active rather than a passive approach to others, and to life. Assertiveness in communication and social relationships involves openness, honesty, and firmness, all with appropriateness and flexibility. The assertive person is confident in a relaxed way, as well as free and spontaneous in social situations.
Human beings have a right, and even a responsibility, to assert their rights.
To do otherwise is to go around half alive, passive, inhibited, cowed and submitting, even suffering such complaints as headaches, stomach disturbances, general fatigue, rashes, and so on. On the other hand, when assertiveness goes too far and takes advantage of others, it is aggression. Aggressive behavior cuts across the rights of others, attacks them and puts them down, it is destructive, hurts people and makes them feel badly. Aggressive individuals may feel on top of things, but they will be watching in case someone tries to better them. They are often defensive, and seldom have many friends.