The PrintFriendly plug-in generates printer-friendly views of the page it is inserted in.  The printer-friendly view is only generated if the user selects it;  the regular template is used by default.

When you place the PrintFriendly tool on a page, you have a few options for how the "printer-friendly version" link is formatted.

The printer-friendly view is generated by replacing the regular page template with a very plain template that shows only the page body.  That means that the printer-friendly view only applies to the page body;  other content will be excluded.

Bugs

If you have any fancy CSS tricks embedded in the page, the printer-friendly view may not reproduce them properly, because its simplified layout may not be able to handle your CSS.