Assertiveness means expressing your point of view in a way that is clear and direct, while still respecting others. Communicating in an assertive manner can help you to minimize conflict, to control anger, to have your needs better met, and to have more positive relationships with colleagues, friends, family and others. Assertiveness is a style of communication that many people struggle to put into practice, often because of confusion around exactly what it means. Sometimes it helps to start by explaining what assertiveness is not:

Aggressive communication
People often confuse assertiveness with aggression, because it involves sticking up for yourself. But the two are actually quite different,The following table gives examples:
AGGRESSION
Force your needs or opinions onto others.
Often involves bullying or pushing others around.
Only your needs matter.
No compromise.
Damages relationships.
May lead to shouting or physical aggression.
Damages self-esteem.
ASSERTIVENESS
Express your needs clearly but respectfully.
Others are treated with respect.
Considers the needs of others as well as yours.
Often compromise.
Stronger relationships.
Using clear language to get point across.
Builds self-esteem.
For example, imagine you are standing in line at the bank and someone else pushes in front of you.
An aggressive response could be to grab them by the shoulder and say loudly:
Hey! What makes you so important that you don’t have to wait in line like the rest of us? This might make you feel better in the short term, but you will probably also spend the rest of the hour feeling annoyed about the interaction. Or perhaps the other person will shout back at you and the situation will get even worse, really leaving you in a bad mood.
A more assertive response could be to gently tap the person on the shoulder and say in a respectful voice:
Excuse me; there is actually a line here. It would be better if you could wait your turn like the rest of us. Chances are you will get a more positive response to this - perhaps the other person will apologize and move to the back of the line, or they may explain their reason for wanting to push in and you may feel happy to do them this favor. They may still respond badly - your assertiveness does not guarantee others will not be aggressive - but at least you will feel good knowing that you did your best and used assertive communication.
Passive communication
Another thing that assertiveness is not is passive communication. Passive communication is:
• Not speaking up for yourself, either because you think your views don’t matter or for reasons like trying to please everyone or ‘keep the peace’
• Putting your needs last to the needs of others
• Allowing yourself to be bullied or ignored
• Often involves speaking quietly or with a hesitating voice, or with body-language like looking at the floor or shrugging the shoulders
• You may undermine your opinions with passive phrases such as: only if you don’t mind, or: but it really doesn’t matter that much to me Passive communication can be damaging to your self- esteem, and also to relationships. If you use a passive communication style, others are more likely to ignore your needs, which may leave you feeling hurt or even angry with them for not treating you better.
So assertiveness is....
Think of assertiveness as the halfway point between passive and aggressive - just the right balance! Here are some tips for practicing being assertive:
• State your point of view or request clearly.
• Tell the other person how you feel as honestly as you can, and remember to listen to what they say as well.
• Tone and volume of voice: how you say it is as important as what you say. Speak at a normal conversation volume, rather than a shout or whisper, and make sure that you sound firm but not aggressive.
• Make sure your body language matches. Your listener will get mixed messages if you are speaking firmly while looking at the floor. Try to look the other person in the eye, stand tall, and relax your face.
• Try to avoid exaggerating with words like always and never. For example: You are 20 minutes late and it is third time this week, rather than: You are always late!
• Try to speak with facts rather than judgments. For example: This report has important information missing, rather than: you have done a bad job again.
• Use “I Statements” as much as possible, rather than “You Statements". For example -"You Statement": You don't care about me. You are inconsiderate and you never make time to call or text me. "I Statement": When you don’t pay me
attention, or call or text me, I feel disconnected and lonely.
• Practice often - assertiveness is a skill that requires you to practice in many different situations. And don’t forget to praise yourself for your good efforts!