Social Network Sites

What is your most important reason for using social networking sites ? In my opinion, the important reason for using social networking sites is to communicate with people, interact with each other and to helps in facing some difficulties in courses we study. I use social networking sites for study. For example, using sites to learn any lessons and it really does help me. Also, Sites are helpful to learn a new language and improve your language skills. Is it possible for you to use them in teaching EFL/ ESL ? Concrete example, please. It is possible to use social networking sites in teaching EFL / ESL. It is so useful to use social networking sites in teaching students. Some of teachers now use these sites in teaching their students. For example, I use a site called schology where teacher can give us an assignment and practice that helps us in a course. Also, she open a discussion where can we add a comment in friend's post. Nowadays, there are a lot of sites helps students in learning and write their own words such as edmodo and blogger.