My mom doesn't understand why I want to have my diary accessible to the world. Let me take a stab at explaining...
Many people advocate keeping a journal to help deal with life issues. They talk about how sometimes you might feel like you must present a happy, successful facade to the world, never admitting the other half of yourself. So they suggest a private journal, where you don't have to worry about others' judging you.
I worry about unlikely things; stupid, I know, and I'm working on it. Anyway, one such worry growing up was that a friend would discover my journals and laugh at me. To protect myself from my friends'(!) imagined ridicule, in elementary school I devised two simple ciphers to encode my journal entries.
By the end of junior high, my need for encryption had lessened. I worried less about my friends finding my journals in the first place. Furthermore, they were my friends, after all. I should have friends who like me for who I really am, I figured, so I shouldn't feel ashamed or embarassed if they read the thoughts recorded in my journals.
Today, this philosophy has expanded further. I feel that I am challenging my own level of self-acceptance by admitting who I am and what I think and feel in the "public" of the internet. I should be comfortable with myself; given that, what do I have to hide? It's true that sometimes I still grimace as I hit the "Post" button. But so long as I've honestly represented events, myself, and others, I view this as merely an opportunity to push myself to accept reality and myself. It's a test, so to speak.