Images are files that a browser displays to an end user, typically found saved as .png or .jpeg.

Image files are complex as they tend to take up a lot of a page’s weight & reduce loading times when left unoptimized.

Web crawlers can’t see images, which is why all images need descriptive keywords embedded in their alt-IMG tag.

This is also what powers image search. 

Image Files & Search Engine Optimization Performance

Image files are essential to having a good user experience, however they need to be properly optimized.

The amount of time unoptimized images add to a page’s loading sequence can dramatically impact User Experience, as well as adversely impact rankings.

WebPageTest.org’s Waterfall view provides a great way to see how your site’s image files are being loaded, which can help identify optimizations that are needed.

Always be sure that all images are loaded where they need to be seen on the page, as loading them before they are needed adds excess time to page load speed.

Alt-Img tags also are a great way to complement your page’s existing written content, as it shows the relationship of the image to the content to bots crawling & indexing your content.