The Insert key (often abbreviated INS) is a key commonly found on computer keyboards.
It is primarily used to switch between the two text-entering modes on a personal computer or word processor. The first is overtype mode, in which the cursor, when typing, overwrites any text that is present on and after its current location. The other is insert mode, where the cursor inserts a character at its current position, forcing all characters past it one position further. On early text-based computing environments and terminals, when the cursor was in overtype mode, it was represented as a block that surrounded the entire letter to be overstruck; when in insert mode, the cursor consisted of the vertical bar that is highly common among modern applications.
Notably, on some recent keyboards, the Insert key is completely absent (except on the numeric keypad), its space instead filled with a double-size Delete key.
On Apple Macintosh computers, the key is rebranded into a Help key. When pressed, the Help functionality of the application in use will be launched. However, when using command line applications, it retains its original functionality for compatibility reasons. On the latest keyboards from Apple it has been replaced by a Fn key.
Modern word processing applications, such as Microsoft Word, operate in insert mode by default, but can still be switched to overtype mode by pressing the Insert key. However, the cursor generally does not change into the letter-surrounding box seen on old text-based systems. Instead, an "OVR" indicator on the status bar is highlighted. However, OpenOffice.org and some text editors retain the original cursor change in addition to the indicator.