Before I start, my words of advice might be similar to
>>2 (maybe my reply will just elaborate yours).
So here, why are you more out-going in real life than online?
Well, there are a lot of possible reasons, but let me give you some I do know:
1. You might be the type of person who shows your true self only to people close to you (best friends, family, etc.), I think the reason is because of fear to be unaccepted, even in the virtual world.
2. You are scared that if you give your opinions on something here, that two cents is not accepted, rejected, and you're then rebuked.
3. You didn't know what to do. The example is like you wanted to reply on a post, but then decided against it, feeling like your opinions didn't matter (maybe because it was similar to someone's who already said it?) or you can't really explain it.
There, only 3 reasons I really know of.
While I'm typing (literally) this, why not give another two cents on how the anonymous element makes people more active and open than in real life, it wouldn't hurt:
1. In the virtual world, no one could hurt you physically.
2. No one can judge us, as we didn't really know each other.
3. We can be whoever we want, like taking a female user name (like my screen name) while you're a male or acting childishly while you're already twenty.
4. While there are some who didn't like us here, the critiques they make hurt less (or didn't hurt at all) as we don't know them and (an important factor) we didn't "hear" or "see" it, but "read" it. Get what I mean?
Okay, there are a lot of reasons for this one but I don't want to list them all as we are using the anonymous element right now also, we know their magic right?
I'm using the effect myself, acting all wise, smarty, and mature like this.