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.
Some languages, such as Bengali, use this key when the number of letters of their alphabet is too large for a standard keyboard.
[3][4] A key labelled with some variation of "Alt Graphic" was on many computer keyboards before the Windows international layouts.
The new Finnish keyboard standard of 2008 (SFS 5966) was designed for easily typing 1) Finnish, Swedish, Danish and Norwegian; 2) Nordic minority languages and 3) European Latin letters (based on MES-2, with emphasis on contemporary proper nouns), without needing engravings different from those on existing standard keyboards of Finland and Sweden.
There is an alternate layout, which differ just in disposition of characters accessible through AltGr and includes the tilde and the curly brackets.
The keyboard layouts in the Nordic countries Denmark (DK), Faroe Islands (FO), Finland (FI), Norway (NO) and Sweden (SE) as well as in Estonia (EE) are largely similar to each other.
At the time of the Fall of communism and opening of commercial import channels this practice was so widespread that it was adopted as the de facto standard.
Nowadays nearly all PCs in Poland have standard US keyboards and use the AltGr method to enter Polish diacritics.
The keymap with the AltGr key: < Romanian standard + the signs mostly pressed with AltGr prints the US keyboard signs Romanian standard> Since release 1903, versions of Windows 10 have the binding: On South Slavic Latin (used in Croatia, Slovenia, Bosnia and Herzegovina, Montenegro and Serbia) and on Czech keyboards, the following letters and special characters are created using AltGr:
On the Swiss German layout, these three keys are labelled èü, éö, and àä, respectively, while on the Swiss French layout, the labels are inverted as üè, öé, and äà; namely, the base layer and the Shift⇧ layer are swapped.
With the UK extended keyboard setting (below), ChromeOS offers a large repertoire of symbols and precomposed characters.
For the diacritics used by Welsh (ŵ and ŷ) and Scottish Gaelic (à, è, ì, ò and ù), the UK extended keyboard setting is needed.
Other operating systems such as Linux and ChromeOS follow this layout but increase the repertoire of glyphs provided.
In the X Window System (Linux, BSD, Unix), AltGr can often be used to produce additional characters with almost every key on the keyboard.
For the diagrams, the grey symbols are the standard characters, yellow is with ⇧ Shift, red is with AltGr, and blue is with ⇧ Shift+AltGr.
The Polish keymap on X-based systems features changed combination for € sign: AltGr+U results in ↓ instead.