Department of Anthropology
San Diego State University

Three Common Punctuation Errors

(This material is largely taken from Harbrace College Handbook, an excellent guide to writing effective English.)

1. Generally speaking, commas go inside the closing quotation marks; so do periods if the quotation ends the sentence. For example,

"Lou," she said, "let's go someplace after class."

2. Do not confuse it's with its. It's is a contraction for it is. Its is the possessive form of it. For example,

Its motor is small. VS. It's [it is] a small motor.

3. The semicolon has two uses: First, it links closely related independent clauses. (An independent clause contains a subject and a predicate.) In this usage the semi-colon acts as a weak period. For example,

Lou walked slowly down the street; Mary ran as fast as she could.

Second, by acting as a stronger mark of punctuation than the comma, it separates sentence elements that contain internal commas. For example,

Watching stupid, sentimental soap operas; eating junk food like French fries, cheeseburgers, and milkshakes; and just doing nothing are my favorite vices.