The basic technique stands in contrast to hunt and peck typing in which the typist keeps his or her eyes on the source copy at all times. Touch typing also involves the use of the home row method, where typists keep their wrists up, rather than resting them on a desk or keyboard (which can cause carpal tunnel syndrome). To avoid this, typists should sit up tall, leaning slightly forward from the waist, place their feet flat on the floor in front of them with one foot slightly in front of the other, and keep their elbows close to their sides with forearms slanted slightly upward to the keyboard; fingers should be curved slightly and rest on the home row. Many touch typists also use keyboard shortcuts when typing on a computer. This allows them to edit their document without having to take their hands off the keyboard to use a mouse. An example of a keyboard shortcut is pressing the Ctrl key plus the S key to save a document as they type, or the Ctrl key plus the Z key to undo a mistake. Many experienced typists can feel or sense when they have made an error and can hit the Backspace key and make the correction with no increase in time between keystrokes.