- Internet experts say changes to Facebook's algorithms have helped "anger groups" like that in Normandy swell to tens of thousands of members.
- This is far from the first time anger fuelled by social media has spilled onto the streets, the 2011 Arab Spring being a prime example.
- Posts raising alarm that France is about to sign its sovereignty away through a United Nations migration pact have racked up hundreds of thousands of views and shares.
With names like "Angry Drivers of Normandy", Facebook groups are the nerve centre of the "yellow vest" protest movement raging across France -- and increasingly, a breeding ground for fake news.
When Facebook's CEO Mark Zuckerberg announced in January that the social media giant was going to start prioritising local news, little did he know it would end up feeding the worst crisis of Emmanuel Macron's presidency.
Internet experts say changes to Facebook's algorithms have helped "anger groups" like that in Normandy swell to tens of thousands of members -- and last month, they spilled onto the streets.
November 17 marked the start of nationwide road blockades against rising fuel prices, which have since ballooned into a mass movement against rising living costs and Macron in general.
With thousands of posts railing against everyone from the president to a shadowy global financial cabal, the groups reflect the leaderless nature of the yellow vests, who subscribe to a variety of different goals.
What's clear is that the groups have been crucial in mobilising protesters, who mainly hail from small-town and rural France.
"We use Facebook for absolutely everything -- informing ourselves, organising ourselves," said Chloe Tissier, a moderator of the "Angry Drivers of Normandy" group, which has more than 50,000 members.
"When a barricade is going up and we don't have enough pallets to set on fire, or food, we put out a post and someone comes to bring them. Doing this by phone would be impossible," she said.
Facebook is also "great because older people are there too", she added. Pensioners, angry that their allowances are being squeezed, make up a sizeable chunk of the movement.
"The yellow vests are not at all a structured movement -- there's no spokesman, it's decentralised. So Facebook is ideal for them," said Tristan Mendes France, who teaches digital culture at Paris-Diderot University.
The change in Facebook's algorithms earlier this year lowered the visibility of content published on pages run by large media outlets, he explained.
"It prioritised content being shared by groups, individual profiles, and local information. This change in the algorithm has boosted the emergence of this movement," he said.
This is far from the first time anger fuelled by social media has spilled onto the streets, the 2011 Arab Spring being a prime example.
Sri Lanka temporarily banned Facebook this year after a wave of hate speech posted on the website helped to spark deadly anti-Muslim riots.