A Military Writer's Handbook
Punctuation

The Comma

The humble comma is the most widely used piece of punctuation, but most writers would not be able to explain the rules of its use. Some writers use commas correctly by instinct. They sense a pause or interruption in the sentence, and know that a comma is necessary to ensure proper flow and sense. However, instinctive comma users tend to overuse commas; indeed, more errors in comma use are a result of adding them in the wrong places rather than leaving them out.

The rules of the road for comma use can be summarized in two basic principles:

  1. Commas are used to link, separate, or enclose parts of a sentence
  2. Never use a comma without a good reason

Commas have four essential functions in a sentence. They can help separate introductory information from the main sentence (introducing); they can add information in the middle of a sentence (inserting); they can be used with conjunctions to combine two complete sentences (coordinating); and they can link a list of sentence elements, including nouns, verbs, adjectives, adverbs, and phrases (linking).

Comma Functions

Coordinating
  Coordinating Comma Exercises (9)
Introducing
  Introducing Comma Exercises (9)
Linking
  Linking Comma Exercises (9)
Inserting
  Inserting Comma Exercises (9)
Commas with Quotations

A comma is usually necessary to set off an identifying phrase that introduces or follows a quotation:

"I was getting jittery," confessed Private Hatton, "but the sergeant was steady as a rock."

You do not need a comma, however, when the quotation is integrated into the substance of the sentence or when the quotation is preceded by that:

General Romeo Daillaire concludes that "in the future we must be prepared to move beyond national self-interest to spend our resources and spill our blood for humanity."

Commas always appear inside the closing quotation mark when a quotation is linked to another part of the sentence:

"However paradoxical it may sound, the armies of the nation-state remain the only viable institutions we have ever developed with the capacity to control and channel large-scale human violence," writes Michael Ignatieff.
Conventional Commas

Common usage, or the whim of a particular editor or writer in antiquity, has determined some uses of the comma that are termed "conventional." Below are examples of some of the more common occasions in which a conventional comma is needed.

  • A comma is needed between parts of a date when they are ordered month, day, year. Current convention omits the comma when day and year appear on either side of the month or when only month and year are given:

    November 11, 2005 but 11 November 2005
    November 2005

  • A comma is used to separate elements in a geographic place:

    Moose Jaw, Saskatchewan

  • When used in a sentence, the parts of an address are separated by and concluded with a comma:

    The celebrated Pan Chancho bakery is located at 44 Princess Street, Kingston, Ontario, about a ten-minute walk from the Royal Military College.

  • Conventional commas are also used after the salutation in personal and formal letters, and after the closing:

    Dear Aunt Margaret,
    Yours truly,