2 Answers

An on-screen display (OSD) is a control panel on a computer monitor or television screen that allows you to select viewing options and/or adjust components of the display, such as brightness, contrast, and horizontal and vertical positioning.

On a computer monitor, an on-screen display is usually activated by buttons on the bottom of the monitor. As an example, one button may bring up a display of the brightness and contrast levels, which may be adjusted by pressing the monitor's up or down arrow buttons.

On a television screen, an on-screen display can usually be activated either through buttons on the television set itself or through the remote control. Television on-screen displays are becoming increasingly complex and interactive. In addition to the visual calibration options, the on-screen display may allow you to view program information, search for programs, or put certain channels under parental control.

http://whatis.techtarget.com/definition/on-screen-display-OSD

Read here on Wiki:  http://en.wikipedia.org/wiki/On-screen_display