Billions of people around the world rely on Facebook, WhatsApp and Instagram to keep in touch with business contacts, family and friends.
Facebook is the largest social media platform in the world, with about 2.9 billion users. Its WhatsApp messaging platform has about two billion users, with more than 1.3 billion using Instagram, the photo and video platform it purchased in 2012.
So when all three networks went down for several hours late on Monday, it was quickly noticed by those who rely on the site for social contact and business.
But what caused the outage?
Facebook first took to competing platform Twitter shortly before 8pm UAE time on Monday to confirm it was aware of issues and was working to resolve them after thousands of people reported outages.
It blamed a "faulty configuration change" for the issues in a post on Tuesday morning from its vice president of infrastructure.
Santosh Janardhan took to Facebook to say “sorry” for the outage and to blame “configuration changes on the backbone routers that coordinate network traffic between our data centres”.
“To all the people and businesses around the world who depend on us, we are sorry for the inconvenience caused by today’s outage across our platforms,” he said.
“We’ve been working as hard as we can to restore access and our systems are now back up and running. The underlying cause of this outage also impacted many of the internal tools and systems we use in our day-to-day operations, complicating our attempts to quickly diagnose and resolve the problem.
"Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centers caused issues that interrupted this communication. This disruption to network traffic had a cascading effect on the way our data centres communicate, bringing our services to a halt.”
Data on the web service monitoring platform DownDetector showed almost 50,000 people had reported the outages on Facebook by just after 5pm.
Some 72 per cent of complaints cited issues with the website, while others were linked to issues with the server connection and the app. More than 75,000 complained about WhatsApp, with 43 per cent reporting issues with its app. Another 28 per cent cited the server connection and 28 per cent raised issues with sending messages.
More than 30,000 Instagram users also had similar complaints, with 51 per cent relating to the app, 26 per cent the server connection and 23 per cent the website.
“Our services are now back online and we’re actively working to fully return them to regular operations," said Mr Janardhan. "We want to make clear at this time we believe the root cause of this outage was a faulty configuration change. We also have no evidence that user data was compromised as a result of this downtime.
"People and businesses around the world rely on us everyday to stay connected. We understand the impact outages like these have on people’s lives, and our responsibility to keep people informed about disruptions to our services," he said.
"We apologise to all those affected, and we’re working to understand more about what happened today so we can continue to make our infrastructure more resilient.”