Six categories of punctuation errors include missing, extraneous, misplaced, excessive, incorrect, and inconsistent punctuation. Each of the following sentences illustrate one of those errors in that order, accompanied by discussion and revision.
1. One man jumped on a police car, leaving its front and rear windows smashed and the top dented in and other protesters sprayed graffiti on another law enforcement vehicle.
The description of the effects of the man’s actions constitute a parenthetical phrase inserted into the main clause, which is “One man jumped on a police car, and other protesters sprayed graffiti on another law enforcement vehicle.” The parenthesis requires punctuation at the end as well as at the beginning: “One man jumped on a police car, leaving its front and rear windows smashed and the top dented in, and other protesters sprayed graffiti on another law enforcement vehicle.”
2. Security-monitoring techniques, that highlight potential incidents and enable a real-time response from the organization, are becoming increasingly important.
The phrase located between the commas is not parenthetical; it is essential to the meaning of the sentence in describing exactly which type of security monitoring techniques are being discussed, so no punctuation should interfere: “Security-monitoring techniques that highlight potential incidents and enable a real-time response from the organization are becoming increasingly important.” (If all security-monitoring characteristics had these capabilities, then that phrase would be a parenthetical one that provides additional information to the sentence, but that would have to be replaced by which to signal that nonessential information follows: “Security-monitoring techniques, which highlight potential incidents and enable a real-time response from the organization, are becoming increasingly important.”)
3. Quarterback Peyton Manning threw for 290 yards and a touchdown, and perhaps more importantly, was not sacked all day.
No comma is required after touchdown, because what follows is not an independent clause. However, “perhaps more importantly” is a parenthetical phrase, so a comma should precede it: “Quarterback Peyton Manning threw for 290 yards and a touchdown and, perhaps more importantly, was not sacked all day.”
4. Style comes from the characteristics that make one garment—a piece of clothing—or accessory—a nonessential item that you wear or carry—different from another.
Too many instances of the same punctuation mark can confuse the reader because the sentence does not provide distinctive cues about its organization and the hierarchy of information presented. If a sentence has more than one parenthetical phrase (in this case, the definitions of garment and accessory), open and closed parentheses, which face each other and more obviously set off what appears between them, should supplant dashes or commas: “Style comes from the characteristics that make one garment (a piece of clothing) or accessory (a nonessential item that you wear or carry) different from another.” (Note that using commas in place of dashes is not an improvement, because the sentence organization is still confusing: “Style comes from the characteristics that make one garment, or piece of clothing, or accessory, or nonessential item that you wear or carry, different from another.”)
5. I’ve been there before, I found it overrated.
Here a semicolon, rather than a comma, is required, because the sentence consists of two independent clauses: “I’ve been there before; I think it’s overrated.” (Alternatively, the sentence could be divided into two separate sentences, or a conjunction could replace the punctuation: “I’ve been there before, but I think it’s overrated.”)
6. Last year, a man agreed to give up his $6,000 drone system and promise not to fly a drone for three years. . . . Last month the FAA announced there are now more registered drone operators in the United States than there are registered manned aircraft.
If one short introductory phrase is followed by punctuation, any similar construction within a piece of writing should adhere to this style: “Last year, a man agreed to give up his $6,000 drone system and promise not to fly a drone for three years. . . . Last month, the FAA announced there are now more registered drone operators in the United States than there are registered manned aircraft.” The same rule applies for any other style, such as how a list is punctuated; if one list is punctuated, for example, “lock, stock, and barrel,” another should not be styled, for example, “rock, paper and scissors.”
