Guest Commentary:  Images of projects are a critical component of any architect or engineer’s portfolio. Photos of completed work, perhaps plans and sketches for work-in-progress, floorplans and elevations are all stock-in-trade. Often, websites contain media files. Perhaps a PDF download of a notable press mention, or a video or audio file of an interview on a project, or a talk on a panel or at a conference.

All are great marketing assets. And online, all these photos, images, files, movies and sounds are all but invisible to search engines. Unless you make them otherwise.

Search engines can't "read" anything but plain old text. A website can teem with lush images, arresting graphics, eye-catching video, toe-tapping music, or fascinating audio interviews and discourses. It can offer downloads of media, including documents, presentations, spreadsheets, and what-have-you. But as far as search engines are concerned, these are all just so many random bits and bytes. A fundamental component of any search engine optimization strategy is to work to make these diverse types of files count toward search visibility.

First and foremost, ensure 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 (a piece of code that tells a search engine “don’t look in this directory). 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 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 files types have in common is a need for clear, descriptive names or titles—by all means not the default name spit out by audio, video or image software, e.g. img230769.jpg. The name of the principal image on this engineering website (http://web.mac.com/blg5/EPI/Home.html), for example is shapeimage_1.png. Visit their online project gallery (http://web.mac.com/blg5/EPI/Project_Gallery/Pages/Beaver_View_Lodge.html) to see a wealth of missed opportunities for branding, context and search engine visibility. Neither visitors nor search engines can make very much sense out of “IMG_8556.” The names of these types of files should be as descriptive as possible and match what the file represents.

If you've got a shot of an office building, for example, call it a "123 Man St. lobby renovation," or "Storefront and façade design, 11 Oak St.," not just plain old "building". For all a search engine knows, this "building" could be a house, a garage or an anthill.

Such descriptive names are not only found by search engine spiders, but often have the added advantage of appearing above, below or by the image itself, enhancing the user experience as well. Beyond any other optimization tactics, file names are accorded the most weight by search engines when it comes to ranking.

It should therefore come as no surprise that 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, like the file name. This is an opportunity to go a little bit broader. That office building renovation, for example, might be in Central City, or conform to green energy standards, or perhaps this is the place to indicate it's a structural update to a landmarked building.

Online merchants might want to use this field to add information such as a manufacturer, product category, or UPC code.
Let's say you use CAD software online. The name of the media file, in this case a photo of the cover art, would obviously be the name of the software package. The "alt" field might include attributes and keywords such as 3D, award-winning, downladable, professional version or the price.

Perhaps the media file in question is named  "Interview with Mies van der Rohe.” In the interview description include the name of the interviewer (boom—you're found for "Walter Cronkite," for example), or list some major projects so the interview might appear in a search for “Seagram Building.”

Keyword strategy, combined with the site's goals, will inform what type 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. This way, even if someone's been careless and named an image file "Bass.jpg," the adjacent text and caption can help a search engine understand if the image depicts a fish, a musical instrument, or a specific brand of shoe. This approach can be broadened to optimizing the entire page the media file resides on in a Web site to further increase the depth of context and relevancy.

Some search experts recommend refreshing or re-uploading media files, particularly if they're targeting highly popular keywords. The thinking goes that freshness is one of many contextual clues search engines consider, which may affect relevancy.

In the case of images, file type matters. Photos should be rendered in .jpg format, logos should be .gif files. The reason is simply that these are standard formats that search engines "expect." Search engines assume 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 a simple gif file represents the logo for Ford, or Sony, or Acme Exterminating.

While 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.

Rebecca Lieb is an analyst at Altimeter Group where she covers digital advertising and media. She’s a digital marketing veteran and author of two books: The Truth About Search Engine Optimization (2009) and Content Marketing (2011).