Reuse images whenever possible
When a browser downloads an image file, it stores it in the disk cache (a space for temporarily storing files on the hard disk). That way, if it needs to redisplay the page, it can just pull up a local copy of the HTML and image files without making a new trip out to the remote server.
When you use the same image repetitively in a page or a site, the browser only needs to download the image once. Every subsequent instance of the image is grabbed from the local cache, which means less traffic for the server and faster display for the end user.
The browser recognizes an image by its entire pathname, not just the filename, so if you want to take advantage of file caching, be sure that each instance of your image is pointing to the same image file on the server (not multiple copies of the same image file in different directories).
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