In computer graphics an television, scrolling or text crawling is the act of sliding a horizontal or vertical presentation of content, such as text, drawings, or images, across a screen or display window. Scrolling is often used to show large amounts of data that could not fit on the viewport all at the same time, this is commonly used in window-based computer displays. The word scroll is derived from the way in which people read scrolls of paper, by rolling up the top of the page and allowing objects lower on the page to move up. Smooth scrolling refers to a scrolling display where text appears smoothly, rather than appearing as a whole line at a time.