If you quickly wanted to print something off the web, hitting the print button would print all the graphics displayed on the screen; things wanted and unwanted. In the age of web, readers should be able to print only the content rather than the website banners, sidebars, footers etc.

A small tweaking is needed in the stylesheet to provide an option for the reader to print only the content. Using a separate stylesheet for printer friendly pages is preferred by most web designers worldwide. The first stylesheet would a normal one with no changes done to it. The second stylesheet will have a display:none element under the sections that are not to be printed.

37signals provides an example of the code and the outputs obtained with and without printer friendly stylesheets.

A simple tweak one every website would help in reducing consumption of printing fuel which is great for the consumer and the environment.