Your Life on Facebook, in Total Recall

Facebook's new format is likely to bring back a lot of old memories. But it could also make it harder to shed past identities.

Remember those karaoke videos from three years ago that somehow wound up on Facebook? They were embarrassing for the few hours they spent at the top of your Facebook profile, and then they were buried under a cascade of new updates.

But on Thursday, Facebook started rolling out a revamped profile feature called Timeline that makes a user’s entire history of photos, links and other things shared on Facebook accessible with a single click. This may be the first moment that many of Facebook’s 800 million members realize just how many digital bread crumbs they have been leaving on the site — and on the Web in general.

For better or worse, the new format is likely to bring back a lot of old memories. But it could also make it harder to shed past identities — something people growing up with Facebook might struggle with as they move from high school to college and from there to the working world.

“There’s no act too small to record on your permanent record,” said Jonathan Zittrain, a law professor at Harvard who studies how the Internet affects society. “All of the mouse droppings that appear as we migrate around the Web will be saved.”

The old Facebook profile page shows the most recent items users have posted, along with things like photos of them posted by others. But Timeline creates a scrapbooklike montage, assembling photos, links and updates for each month and year since they signed up for Facebook.

When Mark Zuckerberg, the founder and chief executive of Facebook, introduced Timeline in September at a developer conference, he described it as a way to get a more comprehensive portrait of someone than by simply reading updates or looking at a profile picture: “We think it’s an important next step to help tell the story of your life.”

Facebook said in a blog post that users could either wait to receive a notification about Timeline on their pages or go to facebook.com/about/timeline to activate it immediately. Eventually all profiles will be switched to the new look, though the company is not saying when. And there will be no switching back.

Some adept users have been able to reach Timeline for weeks using a workaround meant for developers. They said that while the design might be attractive, it was unnerving to realize just how much information they had been feeding into Facebook.

“We’ve all been dropping status updates and photos into a void,” said Ben Werdmuller, the chief technology officer at Latakoo, a video service. “We knew we were sharing this much, of course, but it’s weird to realize they’ve been keeping this information and can serve it up for anyone to see.”

Mr. Werdmuller, who lives in Berkeley, Calif., said the experience of browsing through his social history on Facebook, complete with pictures of old flames, was emotionally evocative — not unlike unearthing an old yearbook or a shoebox filled with photographs and letters.

But while those items would probably live only on a dusty shelf in a closet, these boxes of memories are freely available online for anyone with access to your Facebook page to view.

“It’s unsettling to see the past presented as clearly as the present,” Mr. Werdmuller said. “It’s your life in context, all in one place.”

Several hundred Facebook users shared their initial reactions to Timeline on the company’s blog post. While many appeared to be the kind of denouncements that are generated by any tweak to Facebook’s site, a large percentage welcomed the changes.

“A treat for profile stalkers,” wrote a Facebook user named Mudit Goyal. Another, Joshua Bamberg, said, “If Facebook didn’t change stuff every couple months, we would still be using MySpace.”

And Tatsat Banerjee wrote: “Now our Facebook profile is almost equivalent to a personal Web site. Make no mistake, this is the best update Facebook has ever done till now.”

Analysts say Timeline is a significant evolutionary shift for Facebook. For starters, linking Facebook more closely to memories could make it harder for people to abandon the service for rivals.

To Facebook’s credit, the site lets people edit their life stories and decide which items on their Timelines to hide. And once a switch is made, a user has seven days to review what will be displayed on the page before making it public.

But Nicole B. Ellison, a professor of information studies at Michigan State University who researches how people interact online, said the average Facebook users may not understand how to edit their pages or want to be bothered with it.

“I think for someone who has been on the site for all five of its years,” she said — Facebook opened to the general public in 2006 — “that’s a big undertaking.”

Professor Ellison said the new design could make people’s relationship with Facebook more complex.

“What does it mean to not be able to reinvent yourself after high school, after college?” she said. “Or will people completely go back and edit their histories? And how will that shape the way we view ourselves and our friends?”

Analysts say this is more than just Facebook rethinking a feature or two. The site is trying to help itself to entice advertisers more easily — and to better compete with rivals like Google, said Susan Etlinger, an analyst with the Altimeter Group, a consulting firm that advises companies on how to use technology.

“There is an arms race between technology companies to know as much as possible about the people using their services,” she said.

Timeline is also set up to highlight things like which news articles people are reading, songs they are listening to and recipes they are cooking. Users can choose to have Facebook partners like The Washington Post and the music service Spotify send that information to their Facebook pages. If Facebook could advertise items like concert tickets based on that activity, those ads could be very lucrative.

One of the Facebook designers behind Timeline is Nicholas Felton, who achieved some online fame by publishing detailed annual reports examining and graphing his personal data, such as what he ate and how many miles he traveled. The reports helped him land a job at Facebook. Mr. Felton said there were benefits to seeing one’s behavior compiled in a comprehensive way.

“One year I noticed that I wasn’t going to as many concerts as I could have liked or reading that many books,” he said. “So I was able to modify my behavior around that.”

Mr. Felton said that over time, many Facebook users would come to appreciate Timeline. “Everyone is producing crazy data exhaust these days,” he said. “Showing the value of that data helps move everything forward. It’s pretty exciting and important.”