As shown above, the browser sends a lot of information along with the URL. The Accept header tells you what sort of content the browser prefers, User-Agent specifies which version of what browser it is, Accept-Language contains a list of languages (and dialects) that the user has configured, and Accept-Encoding shows which compression schemes the browser supports. For practical purposes, we only c
![Best practices for using the Vary header](https://cdn-ak-scissors.b.st-hatena.com/image/square/df0d41a5e393bd3e8b5bfab38fe1af1ee8b98b7c/height=288;version=1;width=512/https%3A%2F%2Fwww.fastly.com%2Fcimages%2F6pk8mg3yh2ee%2F1KOvYgrOJeCUndOpjcDOwJ%2F49dc4e3d8e2e3e96fa762b9d567405dd%2FOGimage-default.png%3Fauto%3Davif%26canvas%3D1200%3A630%26width%3D1200%26height%3D630%26fit%3Dbounds%26bg-color%3DFFFFFF)