Caching images is a useful way to speed up the load time on your website. Your browser can save copies of images, style sheets, JavaScript files, or even entire web pages. Therefore, when the site requests the resource again, it does not need to be re-downloaded. There are various available caching options, which are as follows:
Last-Modified
ETag
Expires
Max-Age
Public or Private
Each of these options is not specifically there for images. They will be covered in detail in the next chapter.