If you are a Facebook user, you may have been surprised by the sudden loss of photos over the weekend, following a technical issue that the service was dealing with. All in all, it was reported that upwards of 15% of the photos that Facebook hosts seemed to be missing, replaced by nothing more than a question mark. Given the sheer number of photos on the site, that's a sizable amount, easily in the millions. According to the company, hardware failures were to blame, which cropped up during software upgrades.

That's not to say the pictures are gone forever. Facebook staff says most of them can be restored, with at least some of them already back up and the rest expected to reappear over the next few days. Similar news this week about Google having issues with Google Docs, and the myriad of other issues that any online service can experience, serve as a reminder to always keep a backup of your data.