A good web page uses images to help communicate the message to the reader. However, a Google robot can only read text and not understand images (currently). So how do we tell a Google robot what our images are, in a way that it understands what the page is about to a human?
Three best practices when dealing with images for SEO:
Name the file
Naming the image file something that describes what the picture is, not just an obscure number or group of letters. If you have multiple images that are similar, use a unique number at the end of the name. Some image programs will let you do this automatically as a batch, saving you time.
Bad example: image9382_dn-10-31-2011.jpg
Good example: family-skiing-on-vacation-365.jpg
Include Alternative Text
Alternative text (Alt text) is what is displayed if the image is unable to load. Also, it helps visually impaired web visitors interpret the page via a screen reader. Alt text is a part of the code, and can be updated in various ways depending on your site architecture and content management system. Include a short description of what the image is about; keep it less then 100 characters.
Bad example: (missing) alt = “”
Bad example: (keyword stuffing, nondescript) alt = “skier skiing on skis at ski resort”
Good example: alt = “Adult ski lesson at Vail Resort”
There is no hard set rule for how big an image should be, in kilobytes (KB). But, the smaller an image is the quicker it will load. Quicker load time is directly connected to user experiences, which Google strives to improve. Google has stated pages that load slowly are not ranked as high, because they will deliver a lower user experience.
It is best to upload the image at the size that you want it to appear, rather than scale it down using code snips. This way you’re not adding extra load time to an image that won’t be shown fully anyhow. Uploading a smaller image and stretching it will destroy image quality, so don’t do that either. Use as program like Photoshop that has a ‘save for web’ feature to handle colors and compression adequately.
Align image information to the web page keywords
When naming image files and the alt text, keep in mind the keywords you want the webpage to show up for. Incorporate these keywords into these two places of a image so that Google understands that the image supports the overall purpose of the page, and then what the page is about.
These simple techniques will help move your page up in Google searches!