Search engines like it when every part of your website is optimized; however, even just in regards to the images, when they are optimized, they are much more likely to be pulled up in the images tab on search results.
What does it mean to optimize images? There are 5 parts to an image that have to be optimized.
- Alt tag
- File name
- File size
What do these do? Why should they matter? Well…
- The alt tag is what the search engines read to find out what the image is. Since they don't have eyes to see what an image looks like, they go by words. No alt tag? Search engines will have no idea what the image is, they like to know. This is a great text alternative when browsers are not able to render an image correctly. It will add lots of SEO value to your site. Using plain English is a good idea here.
- File name is what the image is labeled when saved. Why does this matter? Well, it is more information for the search engines to pull when a search is made. An image named "liow20u09508.jpg" will mean nothing when someone searches for a "Ford Mustang 2014", however, an image named, "2014-red-ford-mustang.jpg" will do you good.
- The file size does indeed matter. Why? Well, if your file is too large, then the image will take lots of time to load (load times impact SEO rankings). Make the image a small file size.
- The caption is more information for the search engine and is also good for human viewers. People will read this to find out what is going on in an image and this means less bounce rate (that impacts rankings).