Commas

A comma (,) is a punctuation mark that is frequently used in sentences. Commas separate ideas, add pauses, and help you to list things clearly. They also let us connect words, phrases, and clauses together to make longer sentences. In fact, the comma is one of the most important and commonly used types of punctuation. Without them, sentences would just be messy!

2. Examples of Comma Use

Almost all sentences that aren’t a single independent clause have commas. Here are some examples of the ways we use them:

3. Basic Rules for Commas

There are a lot of ways to use commas in English, and sometimes they can be tricky. But, most of the time, it’s easy to tell where you need a comma, because it just sounds right! Here are ten basic rules and situations about comma use:

a. Use a comma any time you combine two independent clauses with any of the seven coordinating conjunctions (and, but, so, for, or, nor, yet):

b. In most cases, don’t use a comma between an independent clause and a dependent clause:

Only sometimes, when you are showing a big contrast between two things, you can use a comma between an independent and dependent clause:

In these two sentences it’s okay to use a comma because they show a big contrast.

c. Use a comma when a dependent clause is followed by an independent clause:

d. Use a comma when you start a sentence with a word or phrase that introduces it, like this:

e. Use two commas in the middle of sentence to separate out information that isn’t essential to sentence’s meaning, but only provides extra details. One comma goes after the first part, and one goes after the second, like this:

f. Use commas when you are listing three or more things (words, phrases or clauses). Look at these sentences:

We need to use commas here to separate the names, making it clear that they are three separate people. With three or more things, you ALWAYS need to use commas, otherwise your sentence will be confusing.

g. Don’t use commas when you are listing less than three things:

You can see that a comma isn’t necessary here. It isn’t correct to use a comma when you only have two or more things.

h. Use commas when you have more than one adjective in a row describing something:

But, do not use a comma directly between the last adjective and the noun it is describing:

i. Don’t use commas in “that” clauses; restrictive clauses with word combinations like “_____ that _______.”

It may be tempting, but do not use a comma after “that” in sentences like this!

j. Finally, you should use commas when you simply need a pause in a sentence:

4. How to Avoid Mistakes

A good general thing to think about when it comes to commas is that if using one will make your sentence clearer or less confusing, you should do it. When you are using a comma, remember it means “pause,” so try reading your sentence out loud to see if you are pausing at the right time. For example, if you read this sentence aloud:

You can hear that the pauses come at the wrong times in this sentence. So, that means we need to move the commas:

You could add one more comma to this sentence, but it isn’t required:

Furthermore, there are two other specific mistakes that happen with commas: comma splices and run-on sentences.

a. Comma Splice

A comma splice happens when you connect two independent clauses with only a comma, and not a conjunction:

In English, this is a grammar error. It isn’t the proper way to separate these two complete ideas. When connecting two ideas like this, you either need to add a conjunction, or replace the comma with a semicolon (;):

b. Run-on Sentence

A run-on sentence is similar to a comma splice because it also happens when you combine two independent clauses but don’t use proper punctuation or conjunctions:

To fix these run on sentences, we have a few choices. The easiest is to add a comma and a conjunction:

Or, we can separate them into two sentences (but one compound sentence is stronger):