Facebook is redesigning its front page. The News Feed — which is what Facebook's roughly 1 billion users see when they log on to the site — will be rolling out a radical new look over the coming months.
The changes are meant to increase user engagement on the site, make it easier to navigate on mobile phones and provide even more highly targeted advertising.
But any big change also creates a precarious moment in the life of a social network.
Remember Friendster? It was the first social network to achieve large scale success. Founded in 2002 — before Facebook or MySpace — Friendster turned down a $30 million a buyout offer from Google back when that kind of money still turned heads.
At its peak, it had more than 100 million members. Then in 2009 it made some changes to its site, and suddenly Friendster collapsed.
"There was a point where it was really the most important social network," says David Garcia, a researcher at the Swiss Federal Institute of Technology in Zurich.
He analyzed data from Friendster collected during its death throws and has come to some interesting conclusions about what makes an enormous online network vulnerable. In Friendster's case, it began with a specific trigger.
"There was a change in the user interface plus there was the alternative of Facebook," Garcia says.
Friendster's redesigned site was awkward to use, unfamiliar, and some dedicated users left. With each new defection, the site became less useful to the people who remained behind.
"If most of your friends have left the community, you will leave it too," Garcia says.
Every time a friend on your network leaves, a network become less valuable to you. Your calculus changes.
Garcia's autopsy here starts with a simple assumption: that when the costs associated with being on a social network begins to outweigh the benefits, you'll leave.
And what's true for Friendster in 2009, Garcia says, is probably still true for Facebook today.
I ask Ian Fisher, who I met at a coffee shop in Palo Alto, Calif., what would cause him to leave a social network, to cancel his account, delete his photos and abandon it?
"About two years ago, I canceled my Facebook account for about a year," Fisher says. "I did that because I was reading so many article about privacy concerns on Facebook, and I was spending so much of my time on there and realizing I was getting essentially nothing out of it that was good for me."
In 2010, changes in Facebook's privacy policies led lots of people to leave the network. Unlike Friendster, it didn't collapse.
It turns out, the vulnerability of a social networks to the kind of mass defection hinges on how people use the network.
If most people use it to keep in touch with just one or two friends, then when one of those friends leaves, you're' more likely to leave, too. But if you have 1,000 connections, the network is more resilient.
And in Ian Fisher's case, a few years after he left Facebook, he decided to come back: "Because there were people that I didn't know how to get a hold of, but there were my sort of peripheral acquaintances that I didn't get a chance to connect with quite as much."I am still trying to decide whether it's worth it or not. I'm not totally convinced that it is."
It is for now — maybe just to share pictures of his new baby.
But researchers say Facebook still needs to be cautious. When you are tweaking a social network, even one as big and successful as Facebook, you don't want to scare off too many people at one time — or you could create a cascading exodus that is difficult to stop.
And that may be why Facebook is rolling out its latest update very, very slowly.