My sister, Jane, and I went to the museum.
It is just the two of them, no other sisters. While it is great that we now know the sister’s name, the meaning of the sentence does not change.
My sister Jane and I went to the museum.
Oh my, hopefully the other sister(s) were not jealous. By leaving out the commas, Jane is promoted to essential information and indicates that there are additional sisters.
My wife, Mrs. Jones, is on her way.
Great, hopefully she’ll get here soon!
My wife Mrs. Jones is on her way.
Really now? Should this be a case for the law or the comma police?
Commas are called to duty to surround non-restrictive clauses. A non-restrictive clause adds non-essential information to the sentence, i.e. the meaning of the sentence remains clear if the non-restictive clause is deleted.
The April issue of the magazine, which was displayed by the cash register, contained several feature articles.
Commas are non-essential and may take the day off if a restrictive clause supplies relevant information to a sentence.
The book which has a red sticker on the back belongs on the bottom shelf.
After all, we wouldn’t want to put just any book on the bottom shelf.
Often, where there is one comma, there should be a second. When commas are given the task to set off an element within a sentence they work with a partner. One comma waves the starting flag, indicating the begin of the off-set element. The second comma waves the checkered flag, signaling the end of the off-set.
Dates and locations are generally double-teamed by commas.
Tuesday, March 21, is the first day of spring.
The restaurant scene in New York, New York, is vibrant.
As with every rule, there is an exception. If an off-set comma is used within the title of a work and, but the work itself is not off-set by commas because it functions as an sentence component, the second comma may take a holiday.
Sarah, Plain and Tall is the title of a book.
Everyone remembers this rule: the comma in a series. Let’s look at an example.
The buffet features trays of fish, vegetables and crackers and cheese.
We agree there is a tray of fish. But then things become murky. The second tray could contain vegetables and crackers while the cheese flies solo. However, it would also make sense to serve the crackers and cheese on one tray and to reserve a tray for vegetables. One glimpse onto the buffet table can clear this up, but so can the Oxford comma.
The comma after the second to last item in a list of three or more is called the Oxford comma. It is a bit old school, often unnecessary and, therefore, often shunned in the interest of economy of space. However, there are instances where the Oxford comma is indispensible. In the interest of clarity and consistency, I am hanging on to the Oxford comma in my own writing and edit accordingly.
In case you were wondering:
The buffet features trays of fish, vegetables, and crackers and cheese.