There are certain words we say and things we do every day. This is known as being polite or having manners.
We say, "Excuse me" if we need to interrupt someone.
We say, "May I please" if we want to do something.
We have to wait our turn in line.
We do not walk too close to someone. One arm's length is considered polite.
If someone gives you something, we say, "Thank you".
If someone says, "Thank you", we say, "You're welcome".