This is a relatively simple post but it is of HUGE benefit to any programmer wanting to load images onto a page without the use of a Javascript pre-loader. An example of this might be a rollover button.
Create an image that you wish to hide and only appear under certain circumstances.
Define a CSS tag either as part of your HTML <head> section or in an external .CSS file.
.hiddenPic {display:none;}
Now, within your HTML <body> ensure your hidden image uses this tag.
<img src="images/common/rollover.jpg>" alt="Return to Home Page button" border="0" class="hiddenPic" />
Viola!