I've probably had social anxiety since age 4 but didn't realize it until just a few years ago (I'm in my 30's). I always thought social anxiety meant that you get panic attacks in front of other people. I don't have that problem. But I do sometimes get very self conscious in front of people that I don't know very well. And it's hard for me to talk to people I don't know very well. I get so awkward around them. Later on I look back and it's very embarrassing to think the silly things I said or did...as a result of the social anxiety.
I also tend to be kind of shy and reserved around people I don't know very well. My husband is very outgoing, so in comparison to him, I think people often mistake my shyness for being a snob.
I'm an introvert. I don't really like idle chit chat and I'm not very good at it, but I love to talk about interesting topics such as current events, or pop culture, etc.
Usually once I get to really know someone and we have things in common, I feel more relaxed and can be myself around them. But in busy adulthood, there often isn't a lot of time to really get to know someone. Most of the people I know are fortunate enough to have friends that they've known since childhood. (Even if they live in different parts of the country now, they remain friends and see each other when it's possible) In other words, the "getting to know you" phase is well in the past for them. Unfortunately I didn't have good friends when I was growing up. I was friends with the type of people who lose interest in being friends once we aren't in the same place anymore (don't attend school together anymore, don't live in the same neighborhood anymore, etc.)
It can be a real nuisance having social anxiety. Because all around me I can see what I'm missing out on because of it.