First and foremost, ensure that the file or directory in which media files are stored on your server is open and accessible to search engines, and not blocked by a robots.txt file (see Truth 51, “Sometimes you don’t want to be found”). Also, if you use thumbnail images, don’t put the “click to enlarge image” link inside a JavaScript link (a common mistake). When this occurs, search engines cannot access the larger file.

After ensuring that search engines can actually get to media files, plain old text—the fundamental building block of search—is naturally the best place to start optimizing the files themselves. What all these file types have in common is a need for clear, descriptive names or titles. In no case should you use the default name spit out by audio, video, or image software, such as img230769.jpg. The names of these types of files should be as descriptive as possible and match what the file represents.

If you have an image of an apple, for example, call it a “New York State Granny Smith Apple,” or “Olsen Orchard’s Ripe Macintosh Apple,” not just plain old “apple”. For all a search engine knows, this “apple” could be a computer. Or even the Beatles’ record label.

Such descriptive names are not only found by search engine spiders, but often have the added advantage of appearing above, below, or near the image itself, enhancing the user experience as well. Filenames are accorded a lot of weight by search engines when it comes to ranking.

It should, therefore, come as no surprise that those websites that regularly use multiple media files require a naming strategy or protocol to ensure consistency in the names used for graphics, audio, or video.

After giving media files clear, descriptive names, don’t forget to add more descriptive text (or meta data) to the “alt” attribute in the file’s tag. Make it short and to the point, such as with the filename. This is an opportunity to go a little bit broader. That Granny Smith apple, for example, might be from Olsen’s Orchards, or have been a product of the 2008 harvest, or perhaps this is the place to indicate that it’s a sweet, crisp, delicious, and nutritious apple. Online merchants might want to use this field to add information such as a manufacturer, product category, or UPC code. Let’s say you sell DVDs online. The name of the media file—in this case, a photo of the cover art—would obviously be the title of the film. The “alt” attribute might include the names of the actors, director, studio, genre, release year, and any miscellaneous information such as “Academy Award Nominee.”

Perhaps the media file in question is an interview with Tom Cruise by Oprah Winfrey, and the file is named “Interview with Tom Cruise”. The meta data might refer to the film or topic the actor discusses in the interview, refer to the name of the interviewer (boom—you’re found in searches for “Oprah Winfrey”), or list some of the actor’s credits so that the video shows up on more general searches by the actor’s fans.

Keyword strategy, combined with the site’s goals, will help you decide what type of additional data are added in this section.

A caption adjacent to the media file also helps search engines to “understand” what the file is about, because adjacent text helps search engines contextualize what they’ve found and determine relevancy. The goal here is to function much like a newspaper or a magazine by adding keyword-rich captions to media files. By adding adjacent text, even if you’ve been careless and named an image file “Bass.jpg,” adjacent text and captions can help a search engine understand if the image depicts a fish, a musical instrument, or even a particular brand of shoe. This approach can be broadened to optimize the entire page the media file resides on in a website to further increase the depth of context and relevancy.

In the case of images, file type matters. Photos should be rendered in JPG format, and logos should be GIF files. The reason is simply that these are standard formats that search engines “expect”. Search engines assume that a GIF file has 256 colors, standard for rendering graphics such as logos, while photos are rendered in millions of colors. And when using logo files, it’s all-important that the file be named with whatever’s in that logo. No search engine is smart enough to deduce that a simple GIF file represents the logo for Ford, or Sony, or Acme Exterminating.

Although it can be labor-intensive, posting an HTML transcript of the dialogue in an audio or video file goes extraordinarily far in terms of optimizing the actual content of these media files. Given the nature of the medium, it’s best to keep these files short, optimally five minutes or less (particularly in the case of video). Cutting longer media files into shorter segments not only eases viewing, but also affords additional opportunities to optimize the content and to provide extra, spider-able links between episodes or installments. This is particularly helpful in the case of episodic videos or sites that offer podcasts.