I've lived my life online. And though it doesn't bother me to share my personal details with strangers, it sometimes concerns me that I have so little control about what you might learn about me, and about how accurate that information might be. As a result, it's entirely possible that you've corresponded with me... without knowing that it's me.I'm sure that, the last time you interviewed a candidate for a new position, you did a vanity search on the individual. Just how involved has the candidate been in online communities, demonstrating the expertise in, say, Java development, which she bragged about during your phone conversation? What does she say on her work-related blog, and how well do her attitudes fit in with the teams'? And\u2014here's where it begins to get dangerous\u2014what do other people have to say about the individual? Plus, what about the posts you find in which, say, a prospective business ally expressed widely divergent views from yours about a political or religious subject? They aren't relevant, but you know you'll read them; how will they affect your business relationship?I've never cared much about personal privacy; I have always shared a huge amount of myself online. The world knows about my affection for chocolate (dark, please). Yet, it's one thing to contemplate the publicity of our own comments, and the awareness that, between Usenet and archive.org, those comments are written in indelible ink. It's another to worry about what others say about us, especially since those remarks are often found without context. And here's no way to annotate, say, a Usenet posting from 1997, with a comment that "This guy was an utter loon, as you'll see if you read anything else he wrote."A related issue is the difficulty of keeping your personal and work personae separate. Mom probably told you not to say anything in print that would embarass you to find on the front page of the local newspaper the next day, but sometimes you don't know who's reading which newspaper. For example, one remark in The Enterprise Committer: When Your Employee Develops Open-Source Code on the Company Payroll was somewhat-in-passing but is relevant here:Says Leach, "Open-source identity is a harder one to solve, and to be honest, it's one I struggle with all the time. Corporate versus open source is easier; you can always keep e-mail addresses separate, or even use a different name. (This becomes a bit of a problem when you start wanting to go to conferences!)" But generally, she advises, developers should just think about what they're writing, act professionally on mailing lists and remember they're representing the company.Yet, we aren't all professionals, at least not 100% of the time. Last summer, I found myself getting involved in an online community that has nothing whatsoever to what I do for a living. In fact, it's in the "race color creed" set of subjects that would be a Bad Thing to have come up if somone was doing a work-related vanity search. (Nothing embarrassing, just not-your-business.) It's an active discussion forum, and as you may imagine I've never been a successful lurker. If I had used my real name I expect my posts would show up fairly high in a vanity search. As a result\u2014simply to protect my "real self"\u2014I joined the community with an avatar and I have carefully kept any part of my Real Life out of ensuing conversations. (Then for some reason everyone decided that I was male, which was another interesting experience. But I digress.) In an earlier online era, I was friends with a South American Ambassador stationed in Europe; for his sillier online community activity, he used the (sysop-approved) name "Ferdinand Sanz" (and I think most people missed the pun, unless they spoke it aloud with a Spanish accent).However, you don't need to be talking about an intimate or spiritual subject to need to protect your online identity. Sometimes, you need to do so just so you can speak freely, without mentioning the specifics involved (such as the name of your employer). Many online communities, such as an online community for software testing and quality assurance professionals make it Really Okay to use a pseudonym or an avatar, so that you can write, "My shop really screwed up its QA process when it...." It isn't relevant who the company is; nobody cares. What they care about is the open discussion of a problem and the community's conversation about reaching solutions.Those are the actions that work for me. What do you do to protect your own privacy?