We spoke to Bataclan survivors and people in Brussels and Berlin about the way a city is forced to deal with the ramifications of an attack.
Larossi Abballa, 25, reportedly waited outside the policeman's house in a Paris suburb on Monday evening before killing him, his wife and taking their three-year-old son hostage.
A piece that appears in the latest issue of 'Dabiq' heaps praise on the terrorists behind the bombings that took place at Brussels Airport in March while threatening future assaults on Europe.
The latest issue of Dabiq contains a short editorial praising the attacks in Paris, and a photo of the bomb that the group claims brought down a jet in Egypt.
The recent use by US officials of the Arabic acronym "Daesh" to refer to the Islamic State terror group prompted speculation that the word was being deployed as a kind of linguistic diss.
Some are using the Arabic hashtag "Paris is in flames" to celebrate the attack, while others tagged statements of sympathy, or merely shared news.
Volunteers played an "armed defender" in multiple scenarios to see whether the Paris massacre could have gone down differently. Each one died.
The hacktivist collective has targeted an extremist-linked website and Twitter accounts following the deadly attacks in Paris last week.