All of it. Think of it this way. How would you do routing in a React app from scratch: 1. Listen for changes in the URL. 2. Parse the new URL into a routing

All of it. Think of it this way. How would you do routing in a React app from scratch: 1. Listen for changes in the URL. 2. Parse the new URL into a routing object. 3. Pass the routing object down through the component hierarchy. You can do that in maybe 5-10 lines of straightforward code.