You can't build trust or a viable community environment among people who don't have persistent identities. Repeated encounters are what allow people to work collaboratively. But people can have persistent identities that are anonymous -- as long as people can recognize one another.
The GolfWeb Players Club is a perfect example. The shared purpose of this community is for members to help one another improve their golf game. So people want to know: How good is your game? Where do you play? What kind of clubs do you use? They don't care about what you do for a living, what kind of car you drive, or how much money you have. In the Players Club, your identity is connected to the nature of your game -- not to your name or your demographics. In any case, without that identity, it's hard for other people to judge the nature of your participation.
Now, "identity" is different from "reputation" -- another key factor in virtually all Web communities. Identity is based on who you say you are. Reputation is based on what you do and what other people think of what you do. Your reputation provides a context for members of a community to judge the value of your contributions.
On Amazon.com, members can vote on how useful they found another member's book review to be. On eBay, members can rate the quality of their experience with other members, and those opinions get aggregated into a symbol for each member -- a star whose color varies, depending on their rating. On the Motley Fool, members get color-coded stars that appear next to their name when they post messages. These "badges of Foolish achievement" indicate the number of messages that members have posted -- how much they've contributed to the community.
So reputation matters because it helps members of a community make judgments about you, even before they actually deal with you?
You want to have a good reputation, because that helps you accomplish what you're trying to get done in the community. But making your reputation visible to others is also a great way to persuade you to stay in the community. We are all driven by status symbols. It's hard to leave a town in which you've become somebody important. Imagine if your company said, "We're going to make you a vice president, but only on the condition that nobody else knows about it." Would that feel like much of a promotion?
Smart communities understand this principle. On eBay, the highest status symbol is a shooting star. To get a shooting star, you need 10,000 positive-feedback postings from the community. (You also lose points for any negative-feedback postings.) Let's say you have 9,500 positive-feedback points. Are you going to leave that community and go somewhere else, where you're a nobody? If a community has a way of awarding status that is visible to other members, people will strive to achieve it. And a site's status symbol can be a very powerful piece of intellectual property as well.
What else is critical to community?
Boundaries. If just anyone can join your community, then it's not really a community. So you must set boundaries: Who can join? Who can't? How do people join? Who decides whether they belong?
There are lots of ways to implement boundaries. To become an employee of a company, people have to go through an interview process, and they have to receive an offer. On the Web, you can give potential members a quiz. On a stock-picking site, maybe a member's picks have to perform in the top 10% of the community before he or she can be part of an elite subgroup. On an IT site, maybe members need to have a certain Java certification in order to participate.
One reason for having boundaries is to make sure that the people who join a community actually take part in it. But even if you define your boundaries clearly, you can't expect everyone to participate. I often hear people say, "I want every member of my community to participate." That's not natural. The participation rate is almost always the same: Only 10% to 30% of a site's members are active at any one time.
In the real world, of course, it's easy to identify active community members: They're the ones who show up for community events. At a PTA meeting, it might seem like everyone in the organization is involved. But in reality, maybe only 10% of all members actually attended the meeting in the first place.
The virtual space of the Web is a little different. As a Web-community builder, you have to let people discriminate between active members and passive members. For example, the GolfWeb Players Club, the site brings up everybody who meets the criteria that you enter - without discriminating between who's active and who isn't. So, if only 10% are active, and your search brings up 10 members, chances are that only one member will communicate with you. Your reaction will probably be "Hey, most people here aren't doing anything." But that's true of every community! What you really want to do is focus on those who are active.