It's a fitting congruity that the simplest way to gauge Facebook's current woes comes via that other unchallenged behemoth of the internet, Google. Type "How do I ..." into the search engine and one of the first suggestions it comes up with continues: "... delete my Facebook account?" Today it was the ninth top-ranked search term, bringing more than 18m results.

Since it was devised a mere half-dozen years ago by Mark Zuckerberg and three Harvard contemporaries, the social networking site has grown at an astonishing speed, seeing off once-powerful competitors such as Bebo and MySpace. It has also attracted controversies, notably over the issue of a "panic button" for child users.

But this week Facebook has experienced perhaps the closest thing to a crisis in its brief history, with reports of an emergency staff meeting at its California headquarters about privacy issues.

Criticism has been mounting since a revamp of the site in December meant users' profiles became publicly accessible by default. Retreating back into anonymity also became an increasingly tortuous process, with profiles now featuring 50 separate privacy settings and 170 options. This was followed in March by more changes, including plans to automatically share users' information with outside websites.

While this has the potential to hugely boost Facebook's revenues through targeted marketing, it has angered campaigners, including the American Civil Liberties Union. This month EU data protection officials wrote to Facebook, calling the privacy changes "unacceptable".

But what seems to have worried the company are calls for Facebook users to wipe their accounts. "Facebook is officially 'out', as in uncool," was the verdict of another California tech pioneer, Jason Calacanis, chief executive of the question-and-answer website Mahalo, calling for a boycott of the "not trustworthy" site.

In a telling echo of Facebook's origin, in April four New York University students started a web appeal for $10,000 (£7,000) to finance a summer holiday creating an open-source alternative to Facebook, called Diaspora. Within a fortnight they had $100,000.

While Facebook disputes accounts of a crisis meeting – it was, the company says, a regular staff discussion – it admits the furore has stung.

Elliot Schrage, Facebook's vice-president of communications, concedes that the privacy changes have been handled badly. He said: "The most important thing for our business is trust. People trust Facebook with their most personal information – the photographs of their family, how they're feeling, the things they care about. What distresses me most is when people believe our changes are born from malevolence or sneakiness. It's our failure that people don't understand what we're doing with the data. That's a mistake in communications."

But could this see Facebook going the way of Bebo, dropping out of fashion in a descent as dizzying as its rise? Industry experts believe this is unlikely.

Ian Maude, from tech analysis firm Enders, said: "They're going to announce shortly they're over 500 million users. That's 40% of everybody on the internet on the face of the planet. Facebook accounts for about 8% of all time spent online. It's a runaway train, it's a phenomenon."