In linguistics, a register is a variety of a language used for a particular purpose or in a particular social setting. For example, when speaking in a formal setting contrary to an informal setting, an English speaker may be more likely to use features of prescribed grammar—such as pronouncing words ending in -ing with a velar nasal instead of an alveolar nasal (e.g. "walking", not "walkin'"), choosing more formal words (e.g. father vs. dad, child vs. kid, etc.), and refraining from using words considered nonstandard, such as ain't. As with other types of language variation, there tends to be a spectrum of registers rather than a discrete set of obviously distinct varieties – numerous registers could be identified, with no clear boundaries between them. Discourse categorisation is a complex problem, and even in the general definition of "register" given above (language variation defined by use not user), there are cases...