Jack´s comment about a friend being someone who can help you in times of need made me think about this. In my opinion online friends can be very good sources of emotional support, sometimes providing more unconditional support and being more easily available than in-person friends. A friendship made online may or may not last, depending on how emotionally intimate and important for emotional support they become. I think a language partner type friendship is most likely to last while both are focused on improving in the target language and is likely to dwindle off when other life goals take precedence. Some of these friendships might last longer than some friendships in-person though because they do not necessarily depend on living geographically close. But online friends do not really replace the need for friends that you can rely on for help to do things or who can give you a hug. Online friends may give you advice but they can not give you a hand when you need a babysitter, come help you when your car stalls, or go out with you to have fun.