A story, the veracity of which is sometimes questioned, is that the internet was designed and created to survive a nuclear war.  It is true that the worldwide network we know today as The Internet was designed by the engineers at DARPA, the Defense Advanced Research Projects Agency.  And it is true that the communications protocols were designed to be self-correcting such that the network can often fix itself without human intervention.  And The Internet is non-hierarchical having no single control center.  So a plausible wartime scenario is that even if New York and Washington were vaporized an Army General in Omaha might still be able to send an email with orders to the troops in Charleston and Buffalo.  With bombs falling all around, communications might be slow and intermittent, but the internet would try to heal itself as best it could to let a few emails through before it crashed again and had to heal itself again.  And this self-correcting process happens hundreds of times per minute.