Alt Gr key
The Alt Gr or Alt Graph key is a typographic meta key used for accessing a third symbol on a key. It is most common in ISO layouts. If there is a fourth symbol, it is often accessed with Shift and Alt Gr together.
For example, the UK layout "4" key will produce "4", "$" and "€" from 4, Shift+4 and Alt Gr+4 respectively. Extensive use of Alt Gr can be found in languages with additional Latin characters (such as Ø and Å) and those with heavy use of accents.
The Alt Gr key replaces the right Alt key found on ANSI keyboards.