One area in which omitting a comma can create confusion is the serial comma (Oxford comma). This is the comma that many use before the conjunction in a list of 3 items or longer.
Example: I am going to the park with Jim, John, and Mary. The comma after John is the Oxford comma.
Some style guides omit this comma.
Example: I am going to the park with Jim, John and Mary. No confusion here. Both methods have the same meaning.
But consider this:
I would like to thank my parents, John, and Elizabeth.
No confusion here -- three thank-yous.
I would like to thank my parents, John and Elizabeth.
Now the question is whether there are three thank-yous or one? Are John and Elizabeth the parents or two other people?
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