Usage guides don’t define words as a dictionary does, and they don’t tell you how to capitalize words or where to put hyphens as a style manual does. Instead they explain the way we use words in English, and the subtle differences between certain words (e.g., affect and effect) that are often confused.

Dictionary of Modern American Usage. (Oxford University Press, 2003). At 928 pages, this comprehensive and complete book represents the gold standard to many in the trade. Its author, Bryan Garner, has been called “the wunderkind of American dictionary-making.”

Merriam-Webster’s Dictionary of English Usage. (Merriam-Webster, 1994). Of the many usage manuals on the market, copy editors often prefer this one, as they do its cousin in the dictionary department. Authoritative, comprehensive, and easy to read, it follows a “descriptive” rather than a “prescriptive” philosophy.

The Careful Writer. (New York: Atheneum, 1977). Theodore M. Bernstein first put together this glossary of stylistic snares in 1965, after a long career as an editor at the New York Times. Bernstein writes oh-so-cleanly, and with occasional sly humor, about usage, which he calls the “spit and polish” that gives writing precision, accuracy, clarity, and color.

The Accidents of Style. (New York: St. Martin’s Griffin, 2010). Another book for those who love splitting hairs—and splitting infinitives. In other words, writers who care about nuance and can tell which false rules deserve to be flouted. Charles Harrington Elster updates The Careful Writer, writing smartly about more than 350 other thorny usage questions.