I saw a sentence that started like this in an email message yesterday.

Problem:
A comma is missing.

Explanation:
The name “John Smith” is essentially an aside in the sentence.

In other words, the sentence could also have been written to begin as “The new manager is …”.

Therefore, inserting “John Smith” in the sentence requires a comma on either side.

Solution:
“The new manager, John Smith, is …”

I saw this today.

Problem:
A comma is missing.

Explanation:
Expressions of happy-birthday wishes are usually abbreviations of a longer sentence along the lines of “Have a happy birthday, Kirk!”, with a comma immediately after the word “birthday” to indicate the pause in speech.

Even though the imperative sentence is abbreviated to drop the “Have a” part of the sentence, the comma should persist.

And, even if one does not appreciate the abbreviation, it should still be clear that a comma is required because of the pause between “Happy birthday” and the person’s name.

Solution:
“Happy birthday, Kirk!”

My wife got the comma-less form of the question in an email message the other day.

Problem:
Inclusion or exclusion of the comma affects the meaning of the question.

Explanation:
A comma in a sentence indicates a pause, so it can change the way that someone reads a sentence and therefore the meaning of the sentence.

My wife got the question as “How are you my sister?”, which effectively asked my wife how she could be the message writer’s sister.

However, given that the message writer is not my wife’s sister and knows that she is not my wife’s sister, what she should have written was “How are you, my sister?”.

This form with the comma would have

• let the message writer ask my wife how she was doing,
• used a comma to indicate a pause, and
• included “my sister” as a term of adoration or nearness.

Solution:
Include the comma to address someone as your sister and to ask her how she is doing. Exclude the comma to ask someone how she can be your sister.