Facebook has apologized after failing to work among its clients around the world for several hours on Monday.
The WhatsApp and Instagram apps - which are also owned by the Facebook company, also failed to work at the same time.
What was the problem?
In short, Facebook systems failed to communicate with the worldwide web.
'It's like someone who has damaged the company's cables in the data center and disconnected them from the internet', explained the website infrastructure company Cloudflare.
The Facebook profile was full of technical issues.
It stated that: "Changes in how they coordinate internet traffic between our data centers have led to issues that cut off these communications".
Why were the network's customers unable to access the service?
The Internet is divided into hundreds of thousands of networks. Big companies like Facebook own their large networks - known as autonomous systems.
When you want to visit Facebook or Instagram or WhatsApp, your computer needs to join its network, using BGP - a type of online postal service.
To be able to connect them directly to the websites they need, BGP looks at all the available ways that data can be used to navigate and use the best way.
On Monday, facebook suddenly stopped providing the information needed by the system to make it work.
It means that not a single person was able to connect with Facebook or its other networks.
To what extent did the situation have consequences?
The disconnection of the service negatively affected businesses and companies around the world.
The Downdetector, which monitors the service outage, reported 10.6 million cases of service outages worldwide - the largest ever recorded.
For many, the loss of that service was just a distraction. But for some small businesses in the developing world who lacked other reliable means of communicating with their customers, it was probably a very big problem.
Similarly, other organizations whose employees have been working in the fields due to the corona outbreak have been relying on WhatsApp to communicate with their colleagues.
How did the incident take place?
Many reports began to emerge at 16:16 BST on Monday that Facebook, Instagram, and WhatsApp were not working.
Initially, this led to common jokes about how people would react and jibes from rivals such as Twitter.
But a short time later it became clear that the situation was even more serious.
Sheera Frenkel, a New York Times technology correspondent, told the BBC that it took a long time to fix the problem because "people who tried to solve the problem couldn't even get inside the building" to find out what caused the situation.
"We still do not know if the problem was due to a software error or a human error."
However, several theories have begun to circulate - with some claiming that someone played foul play on Facebook.
How has Facebook dealt with the problem?
Facebook founder Mark Zuckerberg, after feeling embarrassed, was forced to turn to the rival Twitter network to apologize.
How much has Facebook suffered?
Perhaps the main problem for Facebook itself was the impact it had on revenue and stock prices. Disable means ads are not delivered for more than six hours on its platforms.
It is estimated that the termination of the service may have resulted in a loss of approximately $ 6bn (£ 4.4bn) from Mr. Zuckerberg's personal wealth, with his share falling by almost 5%.
Some estimate that Facebook lost $ 60m in revenue.
The company has also lost its reputation around the world.
