The attacks in Paris on Friday that claimed the lives of at least 128 people have prompted both grief and support from around the world.
US President Obama called it "an attack on all of humanity and the universal values we share," and British Prime Minister David Cameron said he was "shocked" and that the British would "do whatever we can to help."
The attacks in Paris have also provided an opportunity for social media to showcase its most positive trait: the ability to connect friends and relatives instantly, even across national borders.
In the immediate aftermath of Friday night's attacks, Facebook activated its "Safety Check" feature for users in and around Paris. First introduced in 2014, the tool enables survivors of natural disasters or other mass tragedies to quickly and easily tell their Facebook friends that they’re okay.
"My thoughts are with everyone in Paris tonight," Facebook founder and CEO Mark Zuckerberg posted on Facebook Friday evening. "Violence like this has no place in any city or country in the world. We've activated Safety Check, so if you're in Paris you can mark yourself safe or check on your friends and family."
This is the first time that Safety Check has been used outside of a natural disaster, according to CNNMoney.
After Safety Check was activated for the Paris attacks, 4.1 million people marked themselves safe using the tool, and 360 million people were notified that their friends and loved ones were safe, according to Facebook's PR team. In addition, 78 million people have had 183 million Facebook interactions related to the attacks.
Other social media tools also provided a modicum of support to the grieving and wounded.
Google announced that Google Hangout calls to France from any country would be free for the indefinite future.
On Twitter, Parisians responded to the attacks with the hashtag #PorteOuverte, or "Open Door," to either request or offer a safe space to stay.
However, Wired's Molly McHugh notes that because #PorteOuverte has received such a positive response, it has become flooded with people tweeting about how wonderful it is, meaning that messages either requesting or containing information about safe places to stay have moved farther down the field.
"If you’re looking for or offering a safe location, use the hashtag – otherwise, you could be doing more harm than good," she writes.
[Editor's Note: This piece was updated to include the number of people who have been marked safe using Facebook's Safety Check tool.]