#21h20 marks Paris attacks

The call for people of all races, faiths and backgrounds to unite against the terror attacks on "culture and freedom" came in the form of a letter signed by artists and cultural figures on the French version of the Huffington Post.

The letter called on people in Paris and around the world to turn on lights, light candles, play music and make noise in an effort to show "that culture will continue to shine out and to burnish the light of hope and fraternity."

In response, Parisians were out in the street in full numbers taking their city back from the message of hate and fear.

The call for unity is running under the hashtag #21h20 on social media, which was the top trend on Twitter in France and in the top ten globally.