Tennis players are being routinely abused via social media by gamblers angry that they have lost them money. Photo: Nick Ut/AP

Washington – We know things about former civilisations thousands of years ago largely because of tangible records they left.

But today no one keeps physical records. No one writes letters. No one prints photographs.

“When you think about the quantity of documentation from our daily lives that is captured in digital form, like our interactions by e-mail, people’s tweets, and all of the world wide web,” Google vice-president Vint Cerf has said, “it’s clear we stand to lose an awful lot of our history.”

Cerf has even coined a term for it: “The lost century.”

This issue of digital archiving is not new, of course.

It is difficult to access digital information when the file formats or the device they’re stored on become obsolete.

Cerf is concerned with creating a “digital vellum” that would preserve outdated files, no matter their age.

That said, archivists have been able to pull data from decades-old computers and century-old wax cylinders. The really scary risk of loss may be when our data isn’t technically saved to any one physical thing, but held in the “cloud” or by a private company.

After all, companies shut down every day – just ask Carter Maness, the music writer whose career disappeared when several of his past employers shuttered their websites. Or talk to one of the millions of people who – like me! – chronicled years of their lives on Journalspace. The popular blogging platform closed abruptly in 2009 when a disgruntled former employee wiped its database.

Letter-writing is at an all-time low – most of our personal communication takes place digitally – which means your inbox probably contains stuff that’s important to you: e-mails from old friends, photo attachments, family recipes. It is stored only on your e-mail providers’ servers, and they can do with those what they wish. Who knows what will become of them in 10 years or 20?

Here’s another example. Most parents now use Facebook to share photographs of their children – in many cases, those pictures are only online. Facebook seems like a safe haven for photos and other digital memories. It’s a large, stable company. It has introduced a policy to pass on pictures to a named beneficiary in the event of a Facebook member’s death.

But until last week Facebook’s code also contained a bug that would have allowed a hacker to delete every photo from the site.

“We are nonchalantly throwing all of our data into what could become an information black hole,” Cerf told the Guardian.

“We digitise things because we think we will preserve them, but… those digital versions may… be worse.”

There are efforts to reverse this, of course – to preserve the internet for posterity. In 2010, the Library of Congress famously signed a deal with Twitter to begin archiving every one of the network’s public tweets. The Internet Archive has saved copies of more than 452 billion web pages, which will be preserved even if those sites shut down or change.

But while that may help humanity’s legacy, it doesn’t do much for the average internet user who just wants to scroll through old photos in a few years. What about my online journal? Or my baby pictures? Or my Pinterest collection of recipes?

Cerf has some advice: print out everything.

* Caitlin Dewey writes The Post’s The Intersect web channel covering digital and internet culture. http://www.washingtonpost.com/news/the-intersect/