A slider, also known as track bar in Microsoft literature, is an object in a GUI with which a user may set a value by moving an indicator, usually in a horizontal fashion. In some cases the user may also click on a point on the slider to change the setting. It is different from a Scrollbar in that it is typically used to adjust a value without changing the format of the display or the other information on the screen.
Usage with progress bars 
Sliders are also extensively combined with progress bars in the playback of streaming media over a network connection; the combination is primarily necessitated by the need for the designer or developer of the media player's (or media player plug-in, if the media is being played in a browser by itself or through a webpage-embedded applet) user interface to indicate the current progress of the download that is accessible to the user. The progress inside the slider is usually indicated with a color that distinguishes it from the rest of the slider, including the indicator, and is usually shown to inch slightly faster than the indicator; if the connection with the server of the media is constantly forthcoming or has stalled, the progress stalls in the last position of progress, and the indicator is prevented from moving any further save for the user's own movement of the indicator (which does not result in any further playback if moved forward past the current progress limit, but does result in rewinding of the playback if moved backward in the diagonal extent of progress).[clarification needed]