What do you want to demonstrate or hide when using avatar? It looks as if you desire to say something, but put a plaster on your mouth, as if you want to shake hands with friends, but кеер your hands behind your back. Why? Why are you here then? Communication is a two-way traffic, isn't it?
when i was a kid,i just did what i like,never afraid of disappiont anybody.
words can help so there is no need to show your face here.
All people, who have commented you question, Natasha, are right. To my mind the avatar sometimes can explain very good the present mood or the essence of human nature (if human being wants to do it really), sometimes it simply good picture. The most important thing that avatar has not to distract you personally or other human being on italki.com from studying foreign language. If you normal human being today you can place avatar-picture, tommorow - your own photo. When people acquire experience and begin to talk on Skype avatar ceases to play any value. Best regards for you.
@KG_ I agree with you. Some people don't want to let others know who they are because they have undesirable or bad intentions. But my first comment shows clearly that many people -like me- don't like to use their photo not because they have bad intentions or not because they want to hide themselves (their identity). They simply prefer using avatar because they don't see any use of using their photo. They are here just to learn. Maybe they can show their face in private discussions (when chatting with close friends or their teachers). The real photo is, without doubt, necessary in dating sites where people are looking for love and relationships. I hope I make myself clear :)
I think it's really about privacy and these persons' personalities too. It's inevitable to think though that sometimes, people do this to mask some undesirable intention/s.