How To Use Commas

A Quick Reference Guide

From your first years of grade school, you've been taught to use commas, right? I'm sure your first grade teacher covered it all and to this day, you never find yourself questioning whether your current sentence needs one or not. Or maybe not. More than likely, you often find yourself staring at your current composition, wondering whether to insert that tiny little punctuation mark. It baffles the best of us! This quick and easy reference guide will remind you of the basics of comma use and will have you feeling much more confident about your technical writing skills.

  1. Use a comma to separate a list of items. If you are including a list in your sentence that is more than 2 items long, you'll need to use a comma between each word. For example, you might write: "For breakfast I had ham, eggs, toast and bacon". The list of foods is separate by commas. Take note though, that a comma is not needed before the last item in the list because you've got the word and there. Basically, they serve the same purpose. You don't need both and the and sounds quite natural.
  2. Use a comma to separate two adjectives. When you are describing something, you need to place a comma between each descriptive word. (Think of it as a list of descriptive words that need commas between them.) For example, you might write: "His new car was red, shiny, fast and expensive". Each descriptive word had a comma except for the least one. (Yup, you got it. The and is there so you didn't need the comma. Now you're catching on!)
  3. Use a comma when you're addressing someone directly after using a pronoun (by name or title). If you specifically mention someone's name or their formal title after already addressing them as ‘you' or ‘them' etc., it is necessary to place a comma before and after the name or title. For example, you might write: "Will you, Anne, marry me?" or "Do you mind, Jim, if we stop off at the grocery store first?". Notice that the commas act to separate the name from the rest of the sentence. The sentence would make sense on its own without the formal name or title, and so it is necessary to separate this word from the rest of the sentence.
  4. Use commas when interrupting the flow of your sentence. If you are inserting something to throw off the flow of your sentence, use a comma. For example, you might write: "I thought, as I was brushing my teeth, that we might go out for dinner tonight". A phrase in the middle of a sentence should be surrounded by commas.
  5. Use a comma when writing the date. You'll need to use a comma to separate the day of the month, the month, and the year. For example, you might write: "December 25, 2003, was our anniversary". However, there is an exception to this rule. If the year is left out of the date, no commas are needed. For example, "January 22 is my birthday" is not a full date and therefore doesn't require a comma.
  6. Use a comma to separate the towns, states/provinces and countries. When you are referring to a place, you need to separate each part of the place name. For example, you might write: "I was born in Nevada, Las Vegas, in 1978". Notice how there is also a comma after the state. All place names require a comma when you are listing more than one of them.
  7. Use a comma after phrases (half of a sentence) that are more than 3 words long. A phrase cannot stand alone as a sentence. It just doesn't make sense. But phrases are often used as part of a longer sentence and they therefore need to be separated from the part of the sentence that would make sense on its own. For example, you might write: "If I thought you were funny, I would have laughed at that joke." Notice how the first part of this sentence is a phrase and doesn't make sense on its own, so it is separated from the rest of the sentence.
  8. Use a comma before a quotation. If you are ever going to directly quote someone, you need to place a comma before his words begin. For example, you might write: "John was laughing when he said, "You're wearing that to the party?". A comma is the last thing that you should see before the quotation marks begin.

There are a few other situations where you would need to use a comma in your writing. But if you follow these basic tips above, you will have the confidence of knowing that you've applied all the right comma rules. Now you're well on your way to being a successful writer.


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