By their very nature, Facebook (www.facebook.com) and similar social networking sites are a way to share private matters with others--news of yourself and family, opinions, photos, links to other sites, and so on.

But such sites have to tread carefully to avoid stepping on the toes of their more privacy-conscious users.

May 31 was "Quit Facebook Day," a protest organized by Facebook users angry at what they perceived as the site's lack of privacy. The protest failed miserably, with less than 0.01 percent of Facebook users joining in.

Still, as a result of increasing privacy criticisms, Facebook has implemented simplified privacy controls that make it easier to designate who you want to see what, whether its friends, friends of friends, or everyone.

Some Facebook users have no problem showing off photos of themselves and their kids to the world. Others want only those they designate to know anything at all about them. This is as it should be. But you can't please everyone.

By default, unless you change this, Facebook lets anyone see your posts and photos but lets only your friends see more personal information such as your email address and phone number. Recently, one Rhode Island Facebook user went so far as to sue Facebook for this.

Facebook is immensely popular, the second most popular site on the entire Web, behind only Google, according to the Web analytics company Alexa. It has more than 540 million users worldwide.

Like eBay and Microsoft, Facebook is a digital technology company that many of its users love to hate. Like them, it has brought on much of the criticism itself.

Among other things, Facebook has tried to claim as its own property users' photos to promote itself, only to reverse this after a storm of discontent. Previously, Facebook started reporting to users' friends when they went to certain external Web sites that partnered with Facebook, only to reverse this as well. Facebook CEO Mark Zuckerberg in 2009 made the startlingly inaccurate and self-defeating statement that "the age of privacy is over."

With Facebook's huge user base, it's not likely to go belly up any time soon. Still, the previously reigning social networking service, MySpace (www.myspace.com), was overtaken by Facebook in popularity in 2008, according to the Web analytics company comScore. A year later it laid off nearly a third of its workforce.

Some of Facebook's users are actually hoping the same happens to Facebook. Up-and-coming competitors are out there, including Pip.io (www.pip.io) and Appleseed (www.opensource.appleseedproject.org). But both are startups and nowhere near as polished as Facebook.

Other established, successful, and growing sites are similar, but not quite the same, as Facebook. Twitter (www.twitter.com) is more for letting those interested know of your daily activities and LinkedIn (www.linkedin.com) is more for business-oriented networking.

Despite the inevitable criticisms, Facebook has established itself as a part of the very fabric of our culture. One commentator has even christened this "The Age of Facebook." In an article in TechCrunch (www.techcrunch.com), Michael Arrington wrote of Microsoft dominating the technology world in the 1990s and Google the last decade. This decade, he said, belongs to Facebook.

Since its launch in 2004, Facebook has been more popular with younger people, with older folks in general less comfortable in opening their lives to others.

But no matter what your age, Facebook has a lot to offer. Along with providing remarkably convenient ways to keep better in touch with family and friends, Facebook lets you easily find important people in your life that you may have lost touch with years ago. They may let you see a lot about them, or next to nothing.

The tools that Facebook provides along these lines can be very clever. If you become a friend with someone, and that person's daily posts coming into your News Feed about how they're about to eat a yummy chocolate bar become overwhelming, you can simply hide that person's posts from your sight, without that person knowing it. If one of your friends adds a photo to one of their albums and tags you in it, causing it to show up on your Wall, and you don't want that photo on your Wall, you can simply remove your tag from the photo in your friend's album.

The bottom line with Facebook and privacy is that, if you're especially privacy conscious, you should not be a part of a social network or you should take the relatively little time required to learn how to customize its privacy settings to your liking.