The site's name is Seobility Wiki. The URL I reviewed is: https://www.seobility.net/en/wiki/Progressive_Enhancement
According to the Seobility Wiki website, progressive enhancement is "... a design and development strategy for websites that starts with a simple base and adds step-by-step improvements for more powerful systems. It allows developers to design websites that take full advantage of the capabilities of modern browsers and devices. At the same time, it avoids performance and display problems with less powerful devices and older browsers with limited functionality."
Progressive enhancements are needed because the web is constantly evolving, but yet, there are some browsers and systems that are old. By using progressive enhancements, developers start from a common base that older systems and newer systems understand and are able to load. Progressive enhancements reduce the time required to test on different browsers and increases website functionality as well.
The site's home page (https://www.seobility.net/en/wiki/Main_Page) does not validate.
The site's page with the article about Progressive Enhancements (https://www.seobility.net/en/wiki/Progressive_Enhancement) does not validate either.
The home page of the site has 14 errors and page with the article about progressive enhancements has 8 errors.
I would rate the site's design a 5 because it looks nice, but is very simple. Almost too simple. The pages are easy to read and the blue and white complement each other nicely. However, there is a lot of empty white space on all the pages on the right side. Any page a person clicks on in this website has all the content aligned to the left. It feels like there is so much wasted space and it feels like Seobility could do so much more with the design.
I would rate the site's usability a 5 because the navigation is pretty simple. There are a few categories in the far left column, that the user can click and explore. Those pages lead to pages where there are article links alphabetized. The links do lead to very helpful articles on the website, but it seems like there could be a more clear and better way to do this, which is why my rating is a 5. The usability is not bad, but it's not the best either.
The site does meet its purpose. The home page of Seobility Wiki says it is "Your knowledge base for SEO and Online Marketing." The website provides numerous articles about both of these topics and also web design and development.