Brace yourselves as we enter the world of the Comma: misunderstood, mistreated and underestimated. The poor sweet baby! (I’m going to stick to the basics here. I suggest that if you don’t know whether to put one in or not, leave it out. Get an editor or G.O.I (Gramma Obsessed Individual) to make the final decision for you.)

When I was young, back in the time of the dinosaurs, we were told to insert a comma where one would naturally take a breath. That was in the days when corsets were de rigeur and extraordinarily long sentences were a sign of erudition. These two factors guaranteed a plethora of commas running rampant throughout the text. Ironically, just when we finally eliminate corsets and develop decent in-halers for asthmatics, so that we’re all able to take decent breaths, the long sentence is no longer fashionable. As it is, the previous sentence is wobbling precariously on the edge of acceptability. If I had my editor’s hat on I’d have found a way to cut it in two. These days less is best.

What is a comma? It’s the full-stop’s poor cousin. It says, “Take a breath, take a small break, but don’t completely stop.” It links words or phrases but, unlike it’s stronger siblings the semi and full colon, it isn’t strong enough to hold two sentences together. This doesn’t mean it’s weak or unimportant – it’s just different. (So, please don’t judge.) The careful application of a comma in the right place will determine the intent of a statement. Put in the wrong place it can drastically change the meaning. Without this cute and curly punctuation mark chaos could ensue.

When does one use a comma?
Lists:
The comma separates the individual items in a list, or a series of phrases, thus bringing clarity and a sense of order. The “and” is the indicator that the list is about to end. The conjunction (joining word) performs the same function as the comma, so an extra comma is unnecessary. (See how the comma joined those two phrases? Neat, hey?)
(1) When I have some free time I like to read, watch television, play computer games or soak in the spa.
(2) I had eggs, toast and orange juice for breakfast.
If you wish to add a comment or qualifier after the list, you must use another comma. EG: I wolfed down the eggs, toast and orange juice, while Fred waited patiently.
Extra information: Commas are used in a similar fashion to brackets when a qualifying phrase is added into a sentence. We’re talking about the phrases that, if left out, won’t affect the overall structure of the sentence. EG: The little town, nestled at the foot of Mount Doom, had seen better days.
Other important bits:
(1) Use a comma before a personal name. EG: “Thank you, Kylie,” John said. The name is there to let the reader know to whom John is speaking. It’s an added extra.
(2) Use a comma before “which” but never before “that”. EG: I put it on the table, which was a big mistake. EG: I put it on the table that stood near the door.

I expect most of you know the wonderful example using the panda and the bamboo shoots. But, just in case you haven’t seen it, here it is.
The panda eats shoots and leaves. = The panda consumes the shoots and leaves of the bamboo plant.
The panda eats shoots, and leaves. = The panda consumes some bamboo shoots and then leaves the restaurant.
The panda eats, shoots, and leaves. = The panda consumes some bamboo, fires a pistol, and then leaves the restaurant.

See what power commas have? Use them wisely my friends.