Why has Facebook's Mark Zuckerberg taped over the webcam and microphone on his MacBook?
It often seems like the height of paranoia; the technological equivalent of wearing a tin-foil hat: sticking a piece of tape over your webcam so that hackers aren't watching you.
But it isn't only conspiracy theorists that believe it's a good idea to cover up: Facebook's founder Mark Zuckerberg has resorted to taping over the camera and microphone on his MacBook.
In a post celebrating Facebook-owned Instagram reaching 500 million users on Tuesday, he uploaded a photo showing his laptop in the background.
Eagle-eyed observers spotted that the webcam above the screen and the microphone to the left of the keyboard were covered with tape.
While some suggested that the desk Zuckerberg was posing at wasn't his - why would the billionaire founder of one of the most successful companies in the world not have an expansive corner office - he typically does work on the floor among other staff.
The photo shows that even the technically-savvy Facebook boss - presumably better than most at avoiding malware and trojan horses being installed on his computer - is worried about being spied on.
He isn't the first public figure to support the idea though. According to Edward Snowden, the whistleblower who released details of government surveillance programs, GCHQ ran a program called "Optic Nerve" which used Yahoo web chats to capture images from millions of accounts.
James Comey, the director of the FBI, has also revealed that he tapes over his webcam earlier this year.
Zuckerberg covering up will strike many as ironic considering the long-held beliefs of some that Facebook is doing its utmost to eavesdrop on its users. Earlier this month it was forced to deny claims that it is using smartphone microphones to listen to phone calls in order to better target adverts.
Should I tape over my webcam too?
It is certainly possible for hackers to install malware on computers that allow them to turn on a computer's camera and record or take screenshots of what is going on.
The threat of this can be mitigated by taking common security steps - installing anti-virus software, having a firewall, and not clicking any suspicious links in emails.
For those using desktops, the best way to ensure that you're not being watched is simply to unplug your webcam. For laptop users, this isn't an option, so the Zuckerberg approach of covering it up might be best. The Electronic Frontier Foundation even sells a specially-designed sticker set for the purpose.
Mac users are a little safer - a green light next to the webcam is designed to activate any time the camera is being used, so you should be alerted to any unsolicited recording. This isn't always the case, however.