The purpose of the website is to help people learn to code, and learn the propoer coding techniques for different codeing languages.
The page doesn't validate, it has three warnings, and two errors.
I validated the HTML home page. When I ran it through the validator it came back with 14 errors, and five warnings.
I would rate the websites design as a 9 on a 10 point scale, because it has many differet types of coding languages, and because they have different pages for each of the languages with quick search on the right hand side, so you can quickly see what you need. The colors that they choice don't necessarily work together.
On a usability scale I would give it a 10 because it is easy to use, and they are constatanly making their website better, recently they have added videos on how to code and you can now publish a website from their website.
The site meets the purpose it was going for because it gives you tutrials and directions no how to code something with the language that you need to use.