Extended desktop is a feature in a computer that allows a user to extend viewing capabilities by using two or more monitors at the same time. To connect more than one monitor to a computer, the user must have a computer with more than one monitor port. (On most computers, you can add a monitor port by installing a graphics card.) Extended desktop mode allows the user to display a single document or application across multiple monitors, or use each monitor to display a different document or application. It also allows the monitors to have independent resolutions, color depth, and refresh rates. Extended desktop is useful for presentations where the user wishes to display one screen to the audience while reading notes from another (hidden) screen. It is also used to view spreadsheets across several monitors so that all columns or rows can be seen without scrolling, in graphic and Web design to edit an HTML page on one monitor while viewing the rendered Web page on another, and in gaming.