The site name is MDN Web Docs, URL: https://developer.mozilla.org/en-US/docs/Glossary/Progressive_Enhancement. Progressive enhancement is a design philosophy that provides a baseline of essential content and functionality to as many users as possible, while delivering the best possible experience only to users of most modern browsers than can run all the required code. They are needed so web developers can focus on developing the best possible websites while making those websites work on multiple unknown user agents. The websites homepage does validate. The second page validates. There was one error on the first page and one error on the second. Design is a 8/10 I like to see pictures. Useability is a 10/10 everything worked fine. This site meets its purpose.