Indonesian slang (, ), or informal Indonesian language () is a term that subsumes various vernacular and non-standard styles of expression used throughout Indonesia that are not necessarily mutually intelligible. Regional slang from the capital of Jakarta, based on Betawi language, is however heavily exposed and promoted in national media, and considered the de facto Indonesian slang. Despite its direct origins, Indonesian slang often differs quite significantly in both vocabulary and grammatical structure from the most standard form of Indonesia's national language. These expressions are neither standardized nor taught in any formal establishments, but rather function in daily discourse, usually in informal settings. Several dictionaries of bahasa gaul has been published. Indonesian speakers regularly mix several regional slangs in their conversations regardless of origin, but depending on the audience and the familiarity level with the listeners. History Its native name, bahasa gaul (the 'social language'), was a term coined in the late 1990s where bahasa means 'language' and gaul means 'social', 'cool' or 'trendy'. Similarly, the term bahasa prokem (a more outdated name for Indonesian slang) created in the early 1970s means 'the language of gangsters'. Prokem is a slang form of the word préman 'gangster' and was derived from the Dutch word vrijman, which literally means 'freeman'. Indonesian slang is predominantly used in everyday conversation, social milieus, among popular media and, to a certain extent, in teen publications or pop culture magazines. For those living in more urbanized regions of Indonesia, Indonesian slang language often functions as the primary language medium for communication in daily life. While it would be unusual to communicate orally with people on a casual basis with very formal Indonesian, the use of proper or 'good and correct' Indonesian (bahasa Indonesia yang baik dan benar) is abundant in the media, government bodies, schools, universities, workplaces, amongst some members of the Indonesian upper-class or nobility and also in many other more formal situations. Indonesian slang has evolved rapidly. This is, in part, due to its vocabulary that is often so different from that of standard Indonesian and Malaysian and also because so many new words (both original and foreign) are quite easily incorporated into its increasingly wide vocabulary list. However, as with any language, the constant changing of the times means that some words become rarely used or are rendered obsolete as they are considered to be outdated or no longer follow modern day trends. Classification