When the deadly attacks unfolded across Paris last Friday, social media played a crucial role as a tool to help people in the crisis zone, as well as across the world, communicate, help and show their support for France.
Millions took to Facebook, Twitter and Instagram to post messages of support and solidarity.
Facebook activated its Safety Check tool, which allows users to mark themselves or others as safe. The tool, created to help people in times of crisis, has been previously used in times of natural disasters, like after the devastating earthquake in Nepal.
This was the first time it was used for a human caused calamity.
Safety Check determines the location of Facebook users by the city listed on their profile, the last location used in the Nearby Friends product, or where the person last used the Internet. The feature also provides a hub page for users to visit and check which of their friends have checked in as safe, or are in the area.
"In the last 24 hours, since we activated Safety Check: 4.1 million people marked themselves safe using the tool [and] 360 million people were notified that their friends were safe," a Facebook spokeswoman told CNNMoney Saturday.
Since the attacks, Facebook has faced growing criticism that the Safety Check feature was made available to the victims in Paris, while it remains unavailable to people under similar attacks elsewhere in the world, including the twin bombings that claimed more than 40 lives in Beirut a day earlier.
"Many people have rightfully asked why we turned on Safety Check for Paris but not for bombings in Beirut and other places," said Facebook Chief Executive Officer Mark Zuckerberg on his official account Monday.
"Until yesterday, our policy was only to activate Safety Check for natural disasters. We just changed this and now plan to activate Safety Check for more human disasters going forward as well."
Also Saturday, Facebook launched an app that allowed the site’s users to overlay the blue, white and rouge French flag on top of their profile picture to show their support. Zuckerberg used the app to changed his profile picture, and hundreds of thousands of Facebook users followed suit.
Social media platforms also took center stage in co-coordinating help and spreading information.
The Twitter hashtag #PorteOuverte, which means “Open Door” in French, was used in the immediate aftermath of the attacks as a way for Parisians to offer shelter to others who may need a place to stay.
Across the ocean, #StrandedinUS and #StrandedinCanada were developed to offer assistance to those whose travel plans had been disrupted by flight cancellations after the attacks.
Descriptions of loved ones and requests for information accompanied the hashtag #RechercheParis. A Twitter spokesman said it was used more than a million times within 24 hours.
#PrayForParis also became a worldwide trending topic. As of Saturday, it had been used more than 5 million times on Twitter, and 4 million times on Instagram. The hashtag was attached to images of the Eiffel Tower and the French flag, as well as scenes from around Paris.
A simple but powerful image by London-based French artist Jean Julien emerged as a symbol of support for the people of France. The drawing that overlays the Eiffel Tower with a peace symbol with the message of "Peace for Paris" went viral on the Internet.