Our job might be to build web applications, but we can't build apps that rely on networking if we don't know how these networks and the big network that connects them all (this thing called the Internet) actually work. I'll walk through the basics of networking, then dive a lot deeper (from TCP/UDP to IPv4/6, source/destination ports, sockets, DNS, switching, firewalling and even OSPF, VRRP and BGP). Prepare for an eye-opener when you realize how much a typical app relies on all of these (and many more) working flawlessly... and how you can prepare your app for failure in the chain.