As an introvert there are a number things that we hear from time to time. Let me list them out for you so you can get an idea:
"You are so quiet."
"Why do you never go out?"
"Why don't you want to hangout? Don't you like me?"
"You are shy."
"Why are you always alone?"
"You should get out more."
"Are you ok? You are so quiet."
OK. Fair enough. You have the right to ask these questions or make these comments but when I or other introverts ask you or mention the following, why are we considered rude?
"You are so noisy."
"Can you stop talking? In other words, shut up."
"You should shut up more."
First of all, and seriously, how many times do I have to say this? Shyness and introversion are not the same. Not even close. Shyness is the fear of social judgement while introversion is about how you energise.
Let me give you an example. I know many introverts who are very accomplished public speakers. I don't want to blow my own trumpet but I count myself in that category even though I haven't done a lot recently. Shy people would struggle in this situation.
Another example is going to parties. An introvert would go to a party. He or she would talk to a few people. He or she would have a great time. He or she would maybe have a few drinks and then excuse themselves earlier than most of the other people at the party. Why? Because their social energy has run out. They need to to go and recharge, either by themselves or with their significant other.
Before you start saying things to an introvert, think about what it is you are actually saying. Would you like having something similar said to you if the shoe was on the other foot? I very much doubt it.