Image files can be very large, which results in longer loading time for pages. By optimizing images, that time can be cut down and pages including images will load more quickly. Making sure that files are "actual size" -- meaning that they don't need to be shrunk to fit on the page -- can help make files smaller, and prevent image distortion due to the image being resized in the browser.
The accompanying video shows how to use the image editor tool in OU Campus.
If you are working with images in a program like Photoshop before uploading them to your website, you can use the built-in functionality of the software to optimize images for the web. Find out more about image optimization.