My wife and daughter and maybe 3 or 4 close friends: all from college or high school(now in my 50's). I am a Big I-introvert so I am the exception rather than the rule. A great book is Quiet, The Power of Introverts in a World that Can't Stop Talking, by Susan Cain. My T recommended and I found it very comforting. It really resonated with me. It helped me embrace who I am, and not try to live my life for other's expectations.