I’m in total agreement with you that our online persona is FAR from who we really are. As a matter of fact, I would argue that our online persona is who we want to be, or how we wish other people perceived us. You’re spot on with your claims that we only put our best pictures up, and untag our unflattering pictures. And even though people can follow our activity through the newsfeed, we predominantly have control over who can see our profile or track us. Not to mention, we KNOW people are tracking us and can see our profile, so we are very calculated what we say and write, and who was interact with over the web.
One of the main elements about our online persona that differs from our true persona is that online we have as much time as we want to formulate what we want to say. Where I can take my time and consult with my friends, I may be able to response to a post with confidence, smoothness, and maybe even some charming wit. Whereas in real life if a girl, or intimidating person says something to you, you may fumble upon your words or say whatever comes to your mind first; which in my case is usually stupid, immature, offensive, and off-putting. Thank god for texts and facebook right!
A classic example of the liberties we take online, especially when its anonymous was the advent of midd confessionals. That site got way out of hand and people were saying the most hurtful and harmful things to people. When people can hide behind a mask or a false persona they feel empowered and loose all sense of moral or responsible obligation. Who we are online is a protected, calculated, and liberal persona, where are true persona is a genuine portrayal and expression of who we truly are.