This website has references and online tutorials for many coding languages.
The site's homepage as a few errors (five) when run through the validator, but none that affect the performances of the website. There's just a couple warning about the type attribute being unnecessary and one about needing an alt attribute on an image.
The second page also has quite a few errors, seven in total, the most common being that the "type" attribute is unnecessary for JavaScript resources.
I would give the site's design an eight out of ten. The colors and overall design looks nice, but the page is very long so to get to the links at the bottom you have to scroll a lot. I think it would be better if it was more compact.
I'd give the usability a nine out of ten. Again, the amount of scrolling is what I disliked. Other than that the site's usability is great. The buttons are clearly labelled and there's a search function which is very nice.
The site does meet its purpose. We're using it in class and it works quite well.