The Yahoo Style Guide: The Ultimate Sourcebook for Writing, Editing, and Creating Content for the Digital World | St. Martin’s Griffin | 528 pages, $21.99

If you strolled by a copy editor’s desk at any metro newsroom thirty years ago, you would have likely seen, sandwiched between the pica pole and the Carter’s Rubber Cement, a well-worn, dog-eared version of the Associated Press Stylebook. The glue pot and ruler are long gone. And now, in an age when anyone can publish instantaneously to any corner of the world, it’s worth asking whether the stylebook should be discarded as well.

One answer comes not from the AP or the descendants of Strunk and White, but from Yahoo Inc. The company recently published The Yahoo Style Guide, proclaiming it “the ultimate sourcebook for writing, editing and creating content for the digital world.” At more than five hundred pages, and with an accompanying robust Web site, it is remarkable both for what it addresses (everything from hyphenating compound modifiers to abbreviating state names) and for what it says about where journalism is headed in the twenty-first century.

One of the most interesting things about the guide is that it exists at all. Why does the free and open Web need a Fortune 500 multinational to clarify whether Midwest should be capitalized (yes, when referring to the center of the U.S.) or when to use the exclamation point (sparingly)? And why should bloggers, hyperlocal reporters, and online newsletter editors turn to Yahoo when the company has already been eclipsed by Google in search?

The answer, or part of it, is that Yahoo’s content business remains impressively robust, with fifty-six million unique users visiting Yahoo News in June 2010, the company says, citing comScore figures. And Chris Barr, Yahoo’s senior editorial director and the book’s editor, argues that the guide is intended to “raise the level of writing on the Web”—something Yahoo feels the AP hasn’t tackled. “The AP guide is the bible of the newspaper industry. We wanted to address the rest of the world that the AP doesn’t deal with.”

The editors make their priorities clear early on. When writing for the Web, they favor short over long, simple over complex, consistency over laxity. “Online audiences expect far more information, in much less space, in far less time, than ever before,” the preface says. “Attention spans are short, and every pixel counts.”

Thus, as early as the fourth page of the guide, Yahoo reproduces a diagram from an eye-tracking study showing how online readers flit across a computer screen and rapidly size up headlines, photos and other cues to decide whether to click or flee. In admonitory boldface, editors warn that “your content has a few seconds—three or less! —to encourage people to read more…” (So much for that advice on superfluous exclamation points.)

Much of what Yahoo advises would fit within the wisdom offered by a pantheon of great writing experts, from Lynne Truss to William Zinsser. Don’t split infinitives, except when it’d be awkward not to. Use the active voice and present tense whenever possible.

Yet unlike the AP stylebook, which is written in the tone of an unyielding grammar teacher, with rules pronounced from on high, Yahoo’s guide is imbued with a keen consciousness of content users as well as content creators. One chapter is entitled “Identify Your Audience” and urges authors to study usage data, do online surveys and create profiles to adapt their content to readers. Then again, the guide says, don’t assume you know who your readers are. Someone from the other side of the planet who happens across your site will be mystified by language specific to your culture or geography—and confronted by such idioms, that visitor may click off to another site.

Without always saying so, Yahoo is concerned about the tendency of editors to transfer print standards to the Web. For example, newspaper journalists like to use italics to convey everything from emphasis to irony. But as the guide points out, those italics don’t show up in online RSS feeds or search-engine results, so the reader may get a completely different impression from what the author intended. Digital editors are advised to write and insert “alt text” when publishing photos; if some readers, constrained by anything from a slow Internet connection to a visual impairment, are unable to see the image, the text will still convey its content. And woe to the editor who thinks that fixing a mistake moments after it’s published means your readers will never see it. As the guide notes, errors show up instantly in RSS feeds and e-mails, and caching has a way of revealing all kinds of history we might want to forget or erase.

Bill Grueskin is the dean of academic affairs at Columbia University Graduate School of Journalism. He is a former editor at the Miami Herald and Wall Street Journal.