November 19, 2015 11:15 AM EST

During the recent attacks in Paris, Facebook activated a feature that let people in the city let their friends and family know they were safe. Called “Safety Check,” the feature grew out of a project created after the devastating earthquake and tsunami that struck Japan back in 2011.

For everything you need to know about Facebook’s Safety Check, watch the Tech Time video above.

Write to Alex Fitzpatrick at alex.fitzpatrick@time.com and Arpita Aneja at arpita.aneja@time.com.

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