An interactive explainer

The hardest part of streaming video is the part of the internet you do not own.

Netflix can buy more servers and more disks. It cannot buy the link between your internet provider and the rest of the internet, and at 9pm there is not enough of it. So they stopped sending video across it. A copy of the episode you are about to watch is already sitting on a server inside your provider's own building, put there in the middle of the night, before you asked for it. This is one architectural decision, taken apart: what it buys, what it costs, and why you cannot copy it.

CDNs · Edge caching · ISP peering

Networking · Intermediate · 12 min · Why the video you are about to watch is already in your city — an interactive explainer on ViLearn, with a simulation and a knowledge check. All explainers.