Dictionary.net

Extra features added to make it look better than its competitors.

(By analogy with the "toyboxes" on theatre organs).Features added to a program or system to make it moreflavourful from a hacker's point of view, withoutnecessarily adding to its utility for its primary function.Distinguished from chrome, which is intended to attractusers. "Now that we've got the basic program working, let'sgo back and add some bells and whistles." No one seems toknow what distinguishes a bell from a whistle.