How do writers decide when to use another language or switch from one variety of English to another? Even writers who are perfectly fluent in several languages must think for a moment before switching linguistic gears. The key to shifting among varieties of English and among languages is appropriateness: you need to consider when such shifts will help your audience appreciate your message and when shifts may be a mistake. Used appropriately and wisely, any variety of English can serve a good purpose.

One variety of English, often referred to as the “standard” or “standard academic,” is that taught prescriptively in schools, represented in this and most other textbooks, used in the national media, and written and spoken widely by those wielding social and economic power. As the language used in business and most public institutions, standard English is a variety you will want to be completely familiar with. Standard English, however, is only one of many effective varieties of English and itself varies according to purpose and audience, from the more formal style used in academic writing to the informal style characteristic of casual conversation.