Each time you start Dashboard, it displays a handful of widgets on the screen, such as the Calculator, Calendar, and Clock widgets. In case you don’t need a certain widget, such as the Clock widget, you can remove it and replace it with another widget that you find more useful, such as a widget that tracks stock prices.
You can add or remove as many widgets as you want, although the more widgets you display, the more crowded your screen appears. At the very least, you’ll need at least one widget to appear when you start Dashboard. You can choose from the following default library of Dashboard widgets:
Address Book Lets you search for a person stored in your Address Book
Calculator Displays a four-function calculator ...