For the sake of this blog post, I'd like to suggest that there are ostensibly two types of virtual communities, open and closed. Closed communities are those that require an invitation of some sort to be able to participate as an active member. Open communities are those that allow everyone to participate (at least on some level) provided they act accordingly within the scope of the community's standards.
I'm a member of many closed virtual communities, such as Facebook (recent privacy issues notwithstanding), and various Instant Messaging services (both public and private). The barriers to entry into these communities by and large are the simple fact that you must be invited or given permission to enter the community. For example, within my company's internal Jabber IM service, everyone who wishes to participate must request authorization to first use the service (gain initial admission into the community). Subsequently, once given permission to join the community, you must ask individuals within the community for permission to establish a direct relationship (add someone to your buddy list).
Similarly, Facebook, email, and even text messaging all require, to some extent, permission from others to be allowed into the community. Sure, you can text or email anyone you want if you know their address or phone number, but that doesn't necessarily mean that they'll answer you, or allow you to join their community. You must be given express permission, usually in the form of a return "like" communication, for membership to be activated. We can generally assume that if someone lets you "friend" them in Facebook, you have been invited into their community (and likewise). Subsequently, if you text someone and they reply back, engaging in conversation, then you have effectively been invited into their community.
Open communities don't necessarily require permission to join. Instead, these communities are largely established for the purposes of getting like-minded individuals to share information about various subject matter. In these open communities, there are generally two categories of membership. Those who actively engage and participate within the community (established members) and those that wish to simply observe and occasionally engage in conversation (such as ask a question). Membership within these communities typically only requires that individuals agree to and abide by the rules of the community. Non members, who can still participate within the community are usually restricted in their level of participation. For example, members of a community are allowed to post comments, files, and images to the community, while non-members are allowed to lurk and post limited information.
One open virtual community that I've been associated with for a long time (10+ years), is Slashdot. The Slashdot community is devoted to all types of technology discussions. Article submissions are posted by established members, moderated, and then, if deemed "worthy" of appropriateness are posted to the community pages. Fellow members of the community are allowed to post comments, participate in moderating, and even rank fellow member posts for relativeness (distinguishing useful comments from others). Individuals who aren't members of the community are allowed to read articles and post comments in an anonymous fashion. That is, all community members can distinguish with ease, who is an active participant and who isn't. In the case of Slashdot, all non-member contributions to subject matter are relegated to the status of "anonymous coward".
In a nutshell, closed communities require direct invitations or allowance from peers to be invited into their virtual community. Open communities generally allow access to everyone to read and comment in limited fashions. Within these open communities, there are typically two types of members, those who actively participate and those that don't. Active participants are given usernames and allowed higher levels of interaction within the community, such as post moderation, file submission, and in some cases, community management responsibilities. Non-active participants, are given limited membership in the sense that they are usually allowed to read comments and ask questions only.
Now that that's out of the way, let's talk about the extreme. Within any of these virtual communities, open or closed, it's possible and even likely that there are a subset of members who, for whatever reason, exist and participate within these communities in a manner very different from how they'd interact in real space. Others simply can't relate their virtual communities to their real communities and have a hard time understanding the difference. They live in two different worlds.
Is this good or bad? Who knows... I suppose that if it allows you to express yourself and interact with others on some level, that it might actually be beneficial. If, however, you find yourself constantly sitting in front of a computer (phones included), haven't showered and slept in days, and live and breathe by the discussion board's next posting or Justin Timberlake's tweet, you might need professional help.
