It’s the new, Internet-enabled principle of reciprocity (see this page), going something like this: Comment on others’ as you would have them comment on your profile – but don’t go to theirs too much because it’s invading their privacy. Yes, even though they put all that very personal info out there, social-networking social norms are beginning to indicate it’s too aggressive, even a little voyeuristic, to check out people’s profiles before you know them very well. The term USATODAY uses in a story about this is “Facebook stalkers” . This illustrates that social norms are beginning to develop in the social-networking space – not surprisingly, they’re extensions or refinements of those in RL (real life) social lives. But it’s very complicated. Here’s a set of rules one Facebook user told USATODAY: “With close friends, it is always OK to comment on their profiles; they expect it and might even be upset if you don’t. With distant acquaintances, it is almost never OK. It’s those in the middle that are tricky; it’s OK to bring up their profiles only if there is a reasonable explanation for why you were looking at it in the first place.” See also this USATODAY piece with tips for online socializers on how to break up with someone in RL (real life). They include: It helps to announce the breakup online as quickly as possible (clean break), remove him/her contact data from all devices, and don’t check out his or her blog.