FACEBOOK serves as a graveyard for an estimated 50 million people, with three million more Facebook users - at the very least - dying every year.

The social media site dwarfs the world's biggest cemetery, Wadi-us-Salaam in Iraq, which is the final resting place of a mere five million people.

5 Facebook is already the world's biggest graveyard... and it's growing by the day Credit: Getty - Contributor

It's a bleak thought, but our Facebook pages and YouTube comments all have a good chance of outliving us - creating a huge online record of our lives which will endure long after our bodies are dead.

And as social media grows and matures, more and more accounts will turn from cheery markers of people's lives to digital tombstones, zombie profiles which keep shuffling through cyberspace.

Just because someone is dead, it doesn't mean you won't get notifications when it's their birthday or see them pop up in your feed as suggested friends, bringing back jarring, painful memories and serving as a record of every detail of their lives.

Professor Viktor Mayer-Schönberger, author of Delete: The Virtue of Forgetting in the Digital Age, explained the heartbreaking human aspect to this very 21st-century problem.

5 Everything we do online while we're alive may one day make up our digital obituary Credit: Credit: Kevin Britland / Alamy Stock Photo

He told Sun Online: "When people die, family members are told that eventually they have to let go - and they do. But what if the internet doesn't let them let go?

"The problem is that as we are being confronted with all of these digital memories, our own human memory is triggered. It's like we're tethered to this past that we can't escape, which hinders our ability to live in the present."

"One of the problems with social media accounts still being online is that you're not only re-jigging that last memory before the person died, but we may also see a lot of unimportant trivia and be reminded of that too.

"That torpedoes our ability to remember the important things that we should remember, which are drowned out by the sea of additional trivial stuff."

What happens to your social media accounts after you die? Twitter: Any account which is inactive (not tweeted from or logged in to) for six months will be deleted. Instagram: A dead person’s account needs to be reported for Instagram for the site to take action. If Instagram receives proof of death, they will “memorialise” the account, meaning it becomes locked and is prevented from popping up in other users’ feeds. Proven immediate family members can also contact Instagram to have a deceased loved one’s account removed. Google: You can make plans for what happens to your Google account after you die by visiting Google’s Inactive Account Manager. From here, you can decide whether you want a loved one to have access to your info or if you’d rather your account was automatically deleted once your death has been reported to Google. If you can prove your connection to the deceased, Google can allow you to report and close a dead person’s account or, in certain cases, access content from it. Facebook: Once someone’s death is reported to Facebook, their page becomes “memorialised”, meaning the account is secured and then prevented from coming up in notifications or friend suggestions. Proven immediate family members can also request that a loved one’s account is removed from Facebook, although Facebook will never let anyone log in to a dead person’s account. While alive, you can plan for what happens to your account after you die by setting a legacy contact who can manage aspects of your page, like friend requests and profile pictures, after it’s been memorialised.

The Sun Online spoke to Facebook, Instagram and Google about the growing number of accounts belonging to people who have passed away.

But while there are procedures in place for users dying, not one of the social media giants could offer any info about how they plan to deal with the vast number of dead profiles amassing in every corner of the web.

On Facebook, accounts which are proven to belong to dead people are preserved and converted to "legacy" pages, which prevents them from popping up in news feeds or friend suggestions.

But while anyone can configure their Facebook profile to automatically convert to a memorial page after they die, reporting a dead person's account to Facebook is a painful process which needs proof of death and your connection to the deceased.

5 Social media can make it harder to deal with grief by drowning out important memories in a sea of trivial info Credit: Credit: Phanie / Alamy Stock Photo

Likewise, Google users can make use of the "Inactive Account Manager", a tool which lets you set a preference in advance for what happens to your account after your death is reported to Google.

And while Twitter will automatically delete any account which has been inactive for six months, Instagram accounts don't time-out in this way.

Instead, a user's death has to be reported to the site, along with proof, for the account to be deleted or memorialised - freezing it in time and preventing it from cropping up anywhere distressing.

But these measures are unlikely to deal with the sheer volume of dead accounts growing daily on every social media site.

5 Twitter automatically deletes inactive accounts, but other sites don't have ways of dealing with users dying Credit: Credit: Tetiana Vitsenko / Alamy Stock Photo

There are legal questions, too, around whether family members should be allowed to access their loved one's chat history or private photos after they die.

In May last year, a court in Berlin ruled on the case of two parents who had appealed to Facebook to let them see their dead 15-year-old daughter's messages, so they could know whether she was being bullied before she died.

The parents had argued that the unnamed girl's unexpected death, in front of an underground train, could be explained if they could only see their daughter's messages.

But the court ruled in Facebook's favour, saying that heirs do not have a right to read dead relatives' Facebook messages.

Part of the problem was that a friend had reported the death to Facebook, and the account had been memorialised - meaning the girl's mother, who knew her login details, had automatically been locked out.

Facebook argued at the time that any messages sent by the girl would have be sent under the assumption that they were private, and should stay that way.

5 Questions about digital inheritance and death on social media are profound and complex Credit: Credit: Erkan Mehmet / Alamy Stock Photo

But the social media giant does recognise the magnitude of the problem it is facing.

A blog post, on the topic asks: "What should we do with an account of a deceased young woman, for instance, when one of her parents wants to delete the account but the other wants to preserve it as a memorial for friends and family?

"How do we know what the daughter would have wanted?

"And what should we do if they want to see the private messages between the daughter and her friends – friends who are still alive and don’t want their messages to become public?

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"These questions — how to weigh survivors’ competing interests, determine the wishes of the deceased, and protect the privacy of third parties – have been some of the toughest we’ve confronted, and we still don’t have all the answers."

Professor Mayer-Schönberger, of Oxford University's Internet Institute, added: "Forgetting is not a bug, but a feature of the human cognitive system.

"In that sense, forgetting has a cleansing function which permits us to focus on the present rather than being tied to the past."