Courtesy is being polite and having good manners. It is a gracious way of speaking and acting which gives others a feeling of being valued and respected. It is greeting others with respect. "Please", Thank You", "Excuse Me", "Hello", Good-bye", You're Welcome" are not just words. They are courteous expressions that show people you respect them and care about them.
When a person doesn't practice courtesy, people feel insulted and disrespected. They think this person is rude and ignorant, not caring about anyone or anything. Practicing courtesy gives people a sense that they are valued. Courtesy is like a magnet. It makes you attractive to others.