How do you build a network that survives when the rest of the web goes down? It’s a strange question, but one with a surprisingly concrete answer. You can find the networks in Athens, Berlin, and Red Hook, Brooklyn — small-scale traffic webs that let computers connect peer-to-peer without going through the larger web. It’s called a mesh network, a decentralized setup that uses smart routers and messy traffic to create a more local kind of network. And as the idea has taken shape, it’s found supporters ranging from cypherpunks to the US State Department. It’s also an idea with real consequences, as we’ve seen over and over. After the Arab Spring, country after country has struggled to keep the web alive through times of political turmoil, most recently in Turkey and Ukraine.