One of the most overlooked aspects of SEO is images. Most websites have lots of images but few actually apply SEO techniques to them.
Not implementing SEO techniques with your images could mean that you're missing out on valuable traffic from Google Image Search, which is one of Google's most popular properties. Here are 5 SEO tips that can help you capitalize on all of the searches that are being done for images.
Use Descriptive Image Names and Folder Names
If you're using image names like 00103.jpg on your website, you can't expect search engines to easily identify what the image might contain.
Use descriptive image names instead. If your website contains an image of a red iPod Nano, for instance, the image name red-apple-ipod.jpg is better. If you really want to get sophisticated, you can build a folder structure that includes relevant keywords as well (i.e. /products/apple/iPods/red-iPod-nano.jpg).
Unfortunately, a lot of content management systems and ecommerce platforms automatically give uploaded images useless names (and place them into folders with useless names) so you may need to modify your software to achieve better naming and folder structures. But if you have lots of images, doing so may be a worthwhile investment.
Use Descriptive Alt Tags
Another way you can give search engines clues about what's contained in your images is to use descriptive alt tags.
The more descriptive, the better, within reason, of course. You don’t want to be too generic, but at the same time you don’t want your alt tags to contain a Tolstoy novel. For instance, instead of using 'Ford Mustang' as your alt tag, 'This blue 1965 Ford Mustang won best of show' is better.
On my websites, I've noticed that Google Image Search seems to like sentence-form descriptions better and while I won't say that I have enough data to call this observation 100% accurate, it seems logical, as text in sentence-form is likely to contain more descriptive keywords and probably gives search engines a clue that you're not spamming.
On that note, a reminder: do not under any circumstances use keyword stuffing in your alt tags.
Use Descriptive Anchor Text
As with alt text, if you're linking to your images using text, use good anchor text that describes the contents of the image. Most of the time, this probably means that anchor text contains some of the same keywords you've used in the image name and alt text.
Use Larger Images
I've read several reports suggesting that Google Image Search prefers images that are on the larger side. While I have no first-hand evidence of this, it's important to remember that SEO isn't truly effective unless users click on your listings.
Since it does make sense that if someone is searching for an image, he'll probably be more inclined to click on a larger image with higher quality than a smaller image with lower quality, using a larger image seems to be a good approach where available and appropriate.
Focus on the Page
As with all SEO, context is everything. It's not just about naming your image files right, using good alt text, etc. It's about making sure that the pages your images are located on are tasty to search engines too.
When your pages themselves are well-optimized, the implementation of these image SEO tips will be icing on the cake.