Style is the way language functions to reflect the writer's personality and attitudes in particular situations. For example, a letter to a friend would be relaxed, even chatty, in tone, whereas a job application letter would be restrained and deliberate. The style appropriate for one situation may not be appropriate for another.
Standard English can be divided into two broad categories of styleformal and informal. Understanding the distinction helps writers use the appropriate style. However, no clearcut line divides the two categories; in fact, some writing may call for a combination of the two.
Formal writing is most evident in scholarly and academic articles, lectures, and legal documents. Material written in a formal style is usually impersonal and objective, because the subject matter is more important than the writer's personality. Unlike informal style, formal style does not use contractions, slang, or dialect. (See also English, varieties of.) The paragraph you are reading now is written in formal style.
An informal writing style is relaxed and conversational. It is the style found in most personal (as opposed to business) letters and popular magazines. There is little distance between the writer and reader because the tone is personal.
Contractions and elliptical constructions are common. Consider the following passage, which illustrates how an informal writing style may use slang for special effects and have something like the cadence and structure of spoken English while conforming to the grammatical conventions of written English.
Imagine "The Wizard of Oz" with an oversexed witch, guntoting Munchkrns and love ballads from Elvis Presley, and you'll get some idea of this erotic hellzapoppin from writer-director David Lynch. Lynch's kinky fairy tale is a triumph of startling images and comic invention. In adapting Barry Gifford's book Wild at Heart for the screen, Lynch does more than tinker. Starting with the outrageous and building from there, he ignites a slight love-on-the-run novel, creating a bonfire of a movie that confirms his reputation as the most exciting and innovative filmmaker of his generation.
Peter Travers, Rolling Stone
Requests can be made with various levels of formality by varying the helping verb. The level of politeness you use depends on your relationship with the person to whom you are making the request.
Please fax me a copy of that report, [polite request]
Could you please fax me a copy of that report? [more polite]
Would you please fax me a copy of that report? [even more polite]