With Instagram, WhatsApp and Snapchat becoming more and more popular each day, Facebook's place at the top of the social network pile appears to be under threat. In fact, reports abound that Facebook could well be toppled entirely: in 2014, one group of Princeton University researchers went so far as to say that Facebook could lose 80pc of its users by 2017.
Yet in reality, rumours of Facebook's demise appear greatly exaggerated. And one function on the social networking site could well prove to be its salvation.
Billed by one cultural commentator as 'the future of friendship', it seems as though secret, 'closed' groups on Facebook are more popular than one might think.
Six years ago, Facebook debuted its group feature, and users could close them off to the wider public if they so wished.
I am in several closed groups. The thing is, you'll not find mention of them on my Facebook profile, you can't find them through a search, and owing to confidentiality rules, I'm not allowed to share any information outside the confines of the group.
One unnamed group is for journalists (a place to pass on commissioning tips, industry gossip and moan about freelance rates). Another is for Irish feminists, where topics about sexuality, body image and the gender pay gap are disseminated freely and fairly. Another closed group, made up largely of bolshie younger women and topped out at a membership of 1,000, is a safe place for naked selfies, moisturiser recommendations, Tinder disasters and discussion along the lines of 'are my nipples meant to look like that?'
There are several well-known women in some of these groups, and for them it's a space to vent and solicit opinion without fear of repercussion. One friend admits that she doesn't even bother with 'the rest' of Facebook anymore, preferring to log on simply to contact the other posters in her secret group.
Some posts run quite banal; there's much talk on how to record interviews on an iPhone, or how to respond to a text from an interested gentleman caller.
One woman admitted that she was about to meet a very famous married man for sex; another asked for tips on how to safely become a sex worker.
I asked the founder of the group, a woman we'll refer to as Linda (not her real name) as to why she created her group, a 500-strong group of frank, sex positive women.
"At first it became a way to introduce mutual friends with similar interests to each other, and then the conversations were so much fun and so fascinating that people kept asking me if they could add their own friends into the mix," she says.
"I decided to stop allowing people in at 500. If someone new wants to join the group, they need to be screened via me or another friend who does the admin, and someone needs to leave in their place."
In a great many instances, I've not met some of these women, nor am I likely to. Perhaps that's what makes it easier for members in closed Facebook groups to offload personal problems and present themselves at their most vulnerable, needy and real.
Knowing that they aren't likely to go viral or be reposted (amazingly, everyone adheres to this code of conduct), people are brutally frank.
There is no risk that bosses, husbands or boyfriends will ever get wind of the fact that their employee/girlfriend/wife is bitching about them to an online mind-hive. In a secret group like this, a shoulder to cry on, a friend or a cheerleader is never far from reach. And anyone who talks out of turn or breaks the golden rule gets shown the virtual door.
"I've thankfully never had to make anyone leave, and it's great that no one takes the information elsewhere," says Linda. "There have been a few heated posts and a few fights, but in a group of hot-headed women that's probably to be expected."
This of course flies in the face of Facebook proper; also know as the Happiest Place On The Internet. Within the benevolent confines of Facebook, every status update is fiddled and filtered until it depicts just the right message about its poster.
Facebook is where people curate their personal brands, tweaking them and buffing them to a high shine. Facebook's secret groups are a refreshing antidote to all of that: a selfie of a girl I don't know crying after a break-up, next to a picture of a cake my (real-life) friend just baked.
The keyword here is 'safe space'. In several of these closed groups, nudity and secrets abound, but it's not likely that they're going to escape into the wider reaches of Facebook or the internet. In most cases, you need to be invited to join a Facebook group, because they cannot be found by the wider community.
This lends each closed group an air of exclusivity, and last week it was revealed that several of LA's coolest women - Instagram models, reality show contestants, musician's girlfriends, celebrity make-up artists - are part of a secret group, billed as a 'giant online slumber party'.
At last year's Grammy Awards, a singer was reportedly making her way down the carpet when a young woman ran up to her, begging for entry into her secret Facebook group.
No one really knows what happens behind the closed cyber-doors of these groups, but it's safe to say that the shenanigans wouldn't be a million miles away from the secret groups I've been in.
Once, Livejournal and Reddit were places of frank, behind-closed-doors secret interaction, but now Facebook has gotten in on the 'digital clubhouse' craze, its popularity looks set to run and run.
Naturally, the covert nature of the closed group has a downside, and it was only a matter of time before the technology would be used for ill gain. Earlier this year, BBC News reported that paedophiles in the UK have been using secret groups on Facebook to post and swap obscene images of children. Even more worryingly, the police are often a step behind in their investigation, as it's possible to change the name of a secret group or start another one.
While officials had said that Facebok was not doing enough to police the groups and protect children, Facebook's head of public policy told the BBC that he was committed to removing 'content that shouldn't be there'.
In the meantime, the secret world of the closed Facebook group continues to be a place for the good, bad and ugly.
And, given its air of elitism and selectiveness, it's unlikely that the social network's most intriguing feature will remain a secret for long.
So it would seem that Facebook's reputation as a corner of the internet that the cool kids have abandoned could be a misnomer. The cool kids are present and correct; it's just that we don't know exactly where. And, in the event that you haven't been asked behind the velvet rope yet yourself… well, there's always the possibility of creating your own one.