Articles written for publication on A List Apart use an informal, conversational tone, though not at the cost of clarity or correctness. Experts require neither excessive formality nor excessive casualness to express their authority. If you write with ALA’s readership in mind and sound like yourself, you’re most of the way there already.
Our article space is intentionally limited to a single page. There is no room for meandering, no space for encyclopedic completeness. You need to get in, score, and get out. State your idea clearly and quickly. If your tutorial solves a problem, state the problem. Don’t warm up to your subject by preceding it with generalizations. You don’t need to tell our readers that Tim Berners-Lee invented the web before getting to your point.
Experienced web professionals read ALA. If you dumb down your article, you will offend these readers. But our readers come from many backgrounds—a reader who knows all 317 CSS workarounds might not necessarily have heard of Edward Tufte—so take time to define your terms and provide pertinent background information, if only as a link.