During the last decades of the 20th century and especially since the 1990s, Western text communication technologies became increasingly prevalent in the Arab world, such as personal computers, the World Wide Web, email, bulletin board systems, IRC, instant messaging and mobile phone text messaging. Most of these technologies originally had the ability to communicate using Latin script only, and some of them still do not have the Arabic alphabet as an optional feature. As a result, Arabic speaking users communicated in these technologies by transliterating the Arabic text into Latin script. To handle those Arabic letters that do not have an approximate phonetic equivalent in the Latin script, numerals and other characters were appropriated. For example, the numeral "3" is used to represent the Arabic letter ⟨ع⟩ (ʿayn), note the usage of the mirroring technique to create a visual similarity between the Arabic letter and its numeral substitution. Many users of mobile phones and computers use Arabish even when their system supports the Arabic script because they do not always have Arabic keyboards, or because they are more familiar with the QWERTYkeyboard layout for typing.
It is most commonly used by youth in the Arab world in very informal settings, for example communicating with friends or other youths. The Arabic chat alphabet is never used in formal settings and is rarely, if ever, used for long communications. A single communication in ACA rarely exceeds more than a few sentences.
Arabish is used on many public advertisements by large multinationals. Because of its widespread use, large players in the online industry like Google and Microsoft have introduced tools that convert text written in Arabish to Arabic. Add-ons for Mozilla Firefox and Chrome also exist.
Because of the informal nature of this system, there is no single "correct" way, so some character usage overlaps.
Most of the characters in the system make use of the roman character (as used in English and French) that best approximates phonetically the Arabic letter that one wants to express (for example, ب corresponds to b). This may sometimes vary due to regional variations in the pronunciation of the Arabic letter (e.g. ﺝ might be transliterated as j in the Levantine dialect, or as g in the Egyptian dialect).
Those letters that do not have a close phonetic approximate in the Latin script are often expressed using numerals or other characters, so that the numeral graphically approximate the Arabic letter that one wants to express (e.g. ع is represented using the numeral 3 because the latter looks like a horizontal reflection of the former).
Since many letters are distinguished from others solely by a dot above or below the main character, the conversions frequently used the same letter or number with an apostrophe added after or before (e.g. 3' is used to represent غ).
Conservative Muslims, as well as Pan-Arabists and some Arab-nationalists, view Arabish as a detrimental form of Westernization. Arabish emerged amid a growing trend among Arab youth, especially in Lebanon and Jordan, to incorporate English into Arabic as a form of slang. Arabish is used to replace Arabic script, and this raises concerns regarding the preservation of the quality of the language.