Facebook has added a unique feature to its social network: you can now tell the world — or just your family members — that you’re an organ donor.

The company announced the initiative on Tuesday, encouraging its 900 million users to let others know if they are organ donors.

Facebook chief executive Mark Zuckerberg and chief operating officer Sheryl Sandberg announced the effort in an interview with Good Morning America.

In that interview, Zuckerberg said that his relationship with Apple’s late co-founder Steve Jobs inspired him to use the social network for spreading awareness. Jobs underwent a liver transplant while being treated for pancreatic cancer. Zuckerberg’s girlfriend, who is in medical school to be a pediatrician, also encouraged him to add the tool.

In its FAQ section about the project, Facebook said: “More than 114,000 people in the United States, and millions more around the globe, are waiting for the heart, kidney or liver transplant that will save their lives. Many of those people – an average of 18 people per day – will die waiting, because there simply aren’t enough organ donors to meet the need. Medical experts believe that broader awareness about organ donation could go a long way toward solving this crisis.”

As the New York Times points out, it’s a rare move for Facebook, which has been used to spread awareness of social causes in the past, but has rarely asked its users to engage in any sort of social experiment.

Organ donor advocates such as Andrew M. Cameron, the surgical director of liver transplantation at Johns Hopkins Hospital, told the newspaper that the addition of the feature marks “an historic day in transplant,” because the network reaches so many people.

Immediate reaction on Facebook and Twitter has been mostly positive, though some have said they are hesitant to share such a personal decision over a social network.

“Is anyone else mildly freaked out by the prospect of Facebook posting organ-donor status?” wrote one Twitter user. “Don’t get me wrong, I’m a donor on my license,” wrote another. “But its awfully weird to see Facebook entering the organ donation scene.”

For those who may be uncomfortable sharing their organ donor status with the public or their entire network, Facebook is still allowing users to opt to share the information with any subset of their friends or family. Or, of course, you could choose not to share it at all.

To add your organ donor status to your Timeline, add a new “Life Event.” From there, scroll down to the “Health & Wellness” section and choose “Organ Donor.”

If you’re not an organ donor and would like to be one, Facebook also has a link that will let you sign up to become one in your state through Donate Life America, a non-profit partnering with Facebook.

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