Put commas in their place
Get on top of the comma if you want it to help the reader easily grasp the meaning the writer intended, says HUMPHREY EVANS
COMMAS are pesky little varmints, either popping up unwanted everywhere you look or going missing when needed.
First latch on to the idea that in journalistic writing they mark grammatical units rather than pauses or breaths. That instantly reduces the urge to sprinkle them around.
Next give yourself a sense of some of the simpler usages, say in lists such as this, that and the other. Note that in British journalism, commas come between the items in the list — you can think of them as standing in for an “and” — but not in front of the “and” that attaches the final item. “Tom, Dick and Harry”.
Americans have a tendency to make it “Tom, Dick, and Harry”, which means you have to keep a look out when you’re handling copy from the USA. The extra one is called a serial, or Oxford, comma, but even Oxford University these days is advising its academics not to use it.
The rule is always, think of the reader. If a list features more complex items, perhaps themselves containing an “and”, then you can bring the extra comma into play, say when listing departed department stores such as Bourne and Hollingsworth, Marshall and Snelgrove, and Derry and Toms.
Also register the ways that commas can corral bits of sentences. A single comma can cut off something separate at the beginning or end of a sentence, as here.
Doubled-up commas indicate that a section of a sentence, whether short or long, could be dropped out as inessential to the meaning — again, as here; the length is not just immaterial but irrelevant. Quite often, as here, you can just cut it out.
Sub-editors justify their employment by putting in the second comma that writers, particularly under pressure are prone to leave out. I just left one out there: the one that should go after pressure.
Watch out, especially, to make sure commas never cut off the subject of a sentence from its verb. This, however you dress it up cannot be right. Either drop that comma, or put one after the word ‘up’ to cancel it out.