Facebook is suffering the most severe outage in its history, with key services rendered unusable for users globally for much of Wednesday.
The last time Facebook had a disruption of this magnitude was in 2008, when the site had 150m users - compared to around 2.3bn monthly users today, according to the BBC.
Facebook's main product, its two messaging apps and image-sharing site Instagram were all affected.
The cause of the interruption has not yet been made public.
"We're aware that some people are currently having trouble accessing the Facebook family of apps," Facebook said in a statement.
"We're working to resolve the issue as soon as possible."
In response to rumors posted on other social networks, the company said the outages were not a result of a Distributed Denial of Service attack, known as DDoS - a type of cyber-attack that involves flooding a target service with extremely high volumes of traffic.
While Facebook and Instagram have been down, many have turned to Twitter to make jokes about the outage.
The hashtags #FacebookDown and #InstagramDown have been used more than 150,000 times so far.
Many shared jokes about the social media outage leading to the collapse of society, as "nobody remembers how to reach loved ones or eat food without posting updates".