Commas are wonderful tools. They tell a reader to pause, as this one did. They can also tell a reader that some information, called parenthetical information, isn’t needed, as the first two commas in this sentence did.
It’s that parenthetical information we’ll talk about today and next week.
When you name something and then add extra information, whether it’s defining, describing, or otherwise enhancing the thing you named, the added information is called an “appositive.” In a sentence like this, its use is obvious: “Palin, a former governor of Alaska, is thinking about running for president.” The sentence “names” Palin; the information that she was a former governor is not needed to know whom the sentence is discussing. That “former governor” phrase is an “appositive.” Note that it’s set off by two commas; that second one sometimes gets lost in the shuffle, but it’s important.
Sometimes it’s less obvious when information is parenthetical and needs to be set off by commas. Many people have only one spouse, so when you mention the spouse, any other information is, by definition, extra, and so is set off with commas: “Palin introduced her husband, Todd, to the crowd.” But Elizabeth Taylor had eight husbands (or seven, if you count Richard Burton only once). So if you were writing about her life and wanted to mention one, you would do it this way: “Taylor’s husband Eddie Fisher left his first wife, Debbie Reynolds, for her.” Because Taylor already had more than one husband, more information is needed to know which one the sentence is talking about. But because Fisher had only one first wife, her name is an appositive. The more restrictive the naming” information is, the more likely the following information is an appositive.
Similarly, if someone has only one child, any other information is extra, so you can say “Bill and Hillary Clinton’s daughter, Chelsea, was married last year.” But you’d have to say “Todd and Sarah Palin’s daughter Bristol appeared on Dancing With the Stars,” because they have more than one daughter. If you’d said “Todd and Sarah Palin’s twenty-one-year-old daughter, Bristol, appeared on Dancing With the Stars,” the naming phrase “twenty-one-year-old daughter” makes her name superfluous, since the Palins have only one twenty-one-year-old daughter. (If she were a twin, though, her name would no longer be appositive.)
In journalism, though, it’s sometimes difficult to know whether someone is a single child, daughter, spouse, etc., and so whether there’s an appositive phrase involved. It’s more important in obits, profiles, and the like than in ordinary reporting. So sometimes it’s OK to omit the commas, or use them, as you or your stylebook see fit.
Next week, we’ll talk about when commas are needed when the named thing is introduced by an article.
Just keep appositive attitude, and remember that second comma.