Some are easily recognized, but others are not.

Some look shy.  Some look brash and self-abandoned.  Some wear smiles or frowns.  Introversion is not about what you see.

Introversion is about what you don’t see. You don’t see the self-critical internal dialogue; neverending that.  You don’t see the fear or the anxiety.  You don’t see the profound need to be by oneself, especially in reaction to being forced to be around others in situations where being oneself would seem damn near impossible.

Develop amnesia, then go to a party with your “friends”.  What is it like, to know but not to know?  What is it like to be alone?

If you don’t know, you’re probably not an introvert.