Outage was serious for the millions of people worldwide who rely on the social media sites to run their businesses or communicate with relatives, fellow parents, teachers or neighbors.

 The six-hour outage at Facebook, Instagram and Whatsapp was a headache for many casual users but far more serious for the millions of people worldwide who rely on the social media sites to run their businesses or communicate with relatives, fellow parents, teachers or neighbors, the Associated Press reports.

When all three services went dark Monday, it was a stark reminder of the power and reach of Facebook, which owns the photo-sharing and messaging apps.

Around the world, the loss of WhatsApp left many at a loss. In Brazil, the messaging service is by far the most widely used app in the country, installed on 99% of all smartphones, according to tech pollster Mobile Time.

WhatsApp has become essential in Brazil to communicate between friends and families, but also at work — with many businesses using it to stay in touch with customers — at college, and for everyday transactions such as ordering food.

Offices, various services and even the courts had trouble making appointments, and phone lines became overwhelmed.

Hundreds of thousands of Haitians in their homeland and abroad fretted over the WhatsApp outage.

Many of the country’s more than 11 million people depend it to alert one another about gang violence in a particular area or to talk to relatives in the U.S. about money transfers and other urgent issues, while Haitian migrants traveling to the U.S. rely on it to find each other or share key information such as safe places to sleep.

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