Before there was audio on the Web, before there was video, there was photography. Incorporating photos into a Web site, from a home-grown hobby site to a multimedia corporate site, can still be an effective way of both communicating information and looking good.

As with just about anything, though, there's a right way and a wrong way, or more precisely, right ways and wrong ways.

"Usability" guru Jakob Nielsen recently shined his Ph.D. light on how to best use photos on Web sites. Nielsen runs the Useit.com Web site (www.useit.com), has written or edited 12 books on making technology more user friendly, and helps organize a series of conferences on Web page design and other usability issues (www.nngroup.com/events).

One of Nielsen's main tools is "eyetracking," in which he and his colleagues measure where users' eyes are attracted to on a Web page and how much time they spend there.

The most important thing to keep in mind about Web photos, says Nielsen, is to avoid images that merely serve the purpose of dressing up a Web page without being related to the content or purpose of the page.

Photos of pretty girls, stunning sunsets, and lovely flowers that have nothing to do with the site are either ignored by users or even go so far as annoying them, according to Nielsen's studies. He calls such pictures "visual bloat."

Instead of fluffy images that are merely decorative, use photos related to your site that include important visual information.

For personal Web sites, such as blogs, examples of effective use of photography include a portrait of the author. This lets visitors visualize who's talking to them (or who they're talking to), which can help personalize the experience and make it more meaningful.

For business or organizational sites, portraits of the executive team or other key individuals communicates to visitors that they're not dealing with a faceless, impersonal monolith. In contrast, stock photos of unidentified people happily talking to one another or otherwise posing are meaningless filler and are typically ignored.

For e-commerce sites, including eBay, product photos can help shoppers decide between similar products. The more variation in the product category, the more important is the inclusion of good-quality photos. Users spend much more time looking at photos of bookcases, for instance, than photos of flat-panel TVs, according to Nielsen's findings.

With product categories that have a lot of variation, users appreciate the option of clicking on a small "thumbnail" photo to see a larger photo that provides more detail. Nielsen recommends that the clicked-through photo be at least twice as large as the thumbnail, even larger if appropriate. One common mistake, according to Nielsen, is making the clicked-through photo less than 20 percent larger, which can cause visitors to feel they've just wasted their time.

In an earlier study, Nielsen pointed to the importance of cropping photos, which applies to all photos but particularly thumbnails because of their small size. Focus on the most important information communicated by the photo and cut out the rest.

Nielsen's findings about Web photos are much in line with his findings about Web page design in general.

According to the Nielsen school, the best Web sites communicate substantive content and are easy to get around rather than being overly flashy, slow, and difficult to navigate. "On the Web you have design Darwinism--survival of the easiest," said Nielsen in a phone interview.

Nielsen has a two-click rule: Users should be able to find content they're after in two clicks rather than having to burrow several levels down. If information at your site is too hard to find, users may look elsewhere, in a couple of clicks.

Another mistake frequently made results from simple egotism, says Nielsen. Just because Web designers believe they or their sites are important, that doesn't mean they are. "It's not what you think about your site that counts. It's what users think about it," he says.

That's one reason you should avoid "marketese"--exaggerated, self-congratulatory puffery about your organization, your products or services, or yourself. "Web users are skeptical. The more you exaggerate, the more they'll blow you off," he says.

Similarly, avoid garish formatting such as large red characters or flashing words. Like fancy images and fancy words, fancy formatting can come across as self-promotion or an advertisement and will be more likely to be ignored by visitors.

In short, keep it simple. This doesn't mean dumbed down. It means clear, quick, and meaningful--intelligible.