When saving images, be sure to name them by function, not by some visual attribute, because visual attributes might change in the future.

For instance, we have created a web site with blue buttons for navigation and green buttons for submitting forms. If we name the buttons “btnBlue” and “btnGreen” and then later the color scheme of the web site changes, our button names become meaningless.

On the other hand, if we name the buttons “btnSave” and “btnSubmit,” then the sudden order from management to change the color scheme of the site will not fill us with dread and will in fact be relatively painless.