As a flood of family photos, videos and holiday greetings hits the Internet this time of year, online users will swarm the social networking and photo-sharing sites that have become the personal scrapbooks of our time.
But in the shaky and often promiscuous business of the Web, where companies fold and merge at astonishing speed, you can't always trust that those sites will take long-term care of your digital treasures.
Gowalla, a service for users to announce their whereabouts, is closing down. Last October, Google canned its social network Google Buzz. The Web's first major social network, Friendster, overhauled last June to focus on video games.
In many cases the data that people have entrusted to such sites exists in a cyber limbo, and users' rights are unclear.
"People have very personal relationships with the places where they are putting their personal information," said Leslie Harris, president of public interest group the Center for Democracy and Technology. "But your right to that data becomes more complicated with the Internet and the cloud," the system of shared computer storage that allow users to tap into the Web on the go.
The details of a user's rights are often embedded in long legal policies that federal regulators complain are often too confusing and seldom read.
And they are no solace to users like John Metta, 41, who has experimented with a flood of social media sites.
Metta has joined Twitter, photo-posting service Picasa, Gowalla and Google's social networking service Google+.
He's used Gowalla to "check-in" to coffee shops and concerts in Portland, Ore., alerting friends who might want to join him. He's shared pictures of his wife in front of sweeping vistas, part of an online timeline the site has created of where he's been and whom he's met over the past year.
All that information will be deleted after Gowalla's employees move to Facebook to create a new location service. The company said it will notify its 2 million users of ways to download contact lists, photos and other information.
Metta, a software designer, is a bit burned out from trying to maintain all that information online. "At some point you have to just let go and be Buddhist about it," Metta said.
Letting go becomes harder when some of the Web's biggest sites face uncertainty. As Eastman Kodak tries to shore up its finances, questions surround the fate of the photo albums created by its 75 million Kodak Gallery users, some analysts say.
But there are no standardized privacy rules for Web sites, federal enforcement officials say, and consumers encounter a wide range of practices.
And federal enforcement officials are stepping up efforts to protect online privacy amid swift change.
"There is no general legal requirement for companies to get rid of information," said Christopher N. Olsen, the FTC's assistant director of privacy and identity protection. It recently charged Facebook for failing to delete information of past users, even though it said it did.