'Punctuation', according to Eric Partridge (1977, p. 12), an authority on the subject, 'is not something you add to writing, even the humblest: it forms an inescapable part of writing.' The function of punctuation is to help the reader understand what is written by making clear the relationship between the various parts of the sentence. Improper punctuation can, and often does, alter the meaning and confuse the reader. The writer, however, ought not to rely on punctuation to improve a poorly constructed sentence; the sentence should be rewritten.

There are at least fourteen recognized punctuation marks: period, ellipsis, colon, semicolon, comma, hyphen, dash, question mark, exclamation mark, quotation marks, parentheses, brackets, apostrophe, and oblique. Using them correctly is largely a matter of learning a few simple rules and then applying them with common sense. The modern trend is toward inserting only as much punctuation as the sense requires, rather than sprinkling the copy with numerous commas, dashes, and hyphens.

The following sections are intended to serve as a guide to logical punctuation. The order of decreasing importance of the main punctuation marks is period, colon, semicolon, comma.