Non-standard English, also written as nonstandard English, refers to use of English, especially regarding grammar, but also including other aspects of language, that is considered by convention to be sub-standard or not "proper".
That, however, does not mean it is not or cannot be used. Everybody, even the most punctilious language pundit out there, will at some moment of the day or his/her life "slip" into non-standard English, depending on context and company.
Perfectly correct regional variations of English may be considered non-standard by certain people using a subjective barometer of what they consider "correct".
Examples of non-standard English
- ain't is frequently used - even if in a jocular vein - instead of (be) not and (have) not
- gonna for (be) going to
- wanna for want to
- gotta for have (got) to
- don’t for doesn't - as in The Beatles song "Ticket to Ride": "she's got a ticket to ride and she don’t care."