Usage is the conventional use of a language in any given context. You probably change usage levels without ever realizing it; for example, you may talk one way to your parents and another way to your friends. You probably write in an entirely different way when writing an article or essay.
All types of writing vary in usage level. A text message to a friend will be extremely informal (and possibly sloppy). A peer-reviewed research article will be impeccably researched and written in an objective, scientific style. A newspaper editorial and a personal essay will both be subjective and opinionated but might vary wildly in terms of tone and purpose. An email to a friend will be much more informal than an email applying for a job. Depending on the audience and purpose, you’ll have to write at many different usage levels, adjusting your tone, style, and diction.
The term usage also refers to the acceptable way of using certain words and phrases. For example, some people tend to confuse the terms number of (items) and amount of (substance). Instead of saying that fans purchased “a record amount of tickets” (wrong) you should say they purchased “a record number of tickets” (correct).
USAGE TIDBIT
Computers and smart phones have introduced an entirely new level of usage for informal emails, texting, tweeting, and other casual online communication in which abbreviations are common and correct spelling is sometimes rare. This book contains very little coverage of these areas. The only recommendation we offer is to remain sensitive to what’s considered acceptable and unacceptable to your audience. When in doubt, opt for more formal language until you have a better feel for what’s considered acceptable.