W3 Schools offers written tutorials on every web development language there is to know. Take its HTML Quiz, and then try your hand at the CSS Quiz to see if you know your stuff.

Output: The results of executing the CSS, HTML, and JavaScript entered into the sections of the page. Figure A shows jsFiddle loaded in Internet Explorer 9 with empty code panes.

DeepTrawl is a Windows freeware that will help find broken links, validate HTML & CSS, check spellings on your website or blog and more!