What actualy web design is?

I've got great coding skills, I'm full-stack css/html5/js developer and I wanted to improve my design skills. For me this word is connected with visual part of creating anything and giving attention to usability of this thing.

So I've started to look for books and articles about web design and I've realized that actualy most of them talk about web development instead of web design - example here. So what really is web design? Do I need pencil or code editor to train such 'design' skill?