AltGr key

AltGr (also Alt Graph) is a modifier key found on computer keyboards. It is primarily used to type characters that are used less frequently in the language that the keyboard is designed for, such as foreign currency symbols, typographic marks and accented letters. The AltGr key is used to access a third and a fourth grapheme for most keys. Most are accented variants of the letters on the keys, but some are additional symbols and punctuation marks. For example, when the US-International keyboard mapping is active, the C key can be used to insert four different characters: C → c (lowercase — first level) ⇧ Shift+C → C (uppercase — second level) AltGr+C → © (copyright sign — third...