It’s a question I hear all the time: when do you use a comma with and? If you’d like to learn about the Oxford comma, click here. What I’m going to focus on today is joining sentences with and.
Here’s the rule. If there are two sentences, use the comma. If not, omit the comma. Here are two examples:
We loved Hawaii, and we want to go back. TWO SENTENCES: COMMA
We loved Hawaii and want to go back. ONE SENTENCE: NO COMMA
But why? Many people just insert the comma (or leave it out) willy-nilly, without using a rule for guidance. What difference does it make? Answer: A huge difference. And I can prove it.
Take a look at this sentence:
We roasted marshmallows and a squirrel
Pretty nasty picnic! But now read this:
We roasted marshmallows and a squirrel grabbed one.
Much nicer picnic! So how do we make the sentence clear enough so that it can be understood on the first reading?
The answer is to insert a comma after marshmallows. That punctuation mark – a mere wiggly line – tells your brain that the roasting is over. We know that the squirrel introduces something else that happened.
We roasted marshmallows, and a squirrel grabbed one. CORRECT
Let’s try another example. Here’s the beginning of a sentence about a party:
I invited Joe and Alice
Poor Alice – she wasn’t included! But maybe she came to the party after all:
I invited Joe and Alice asked if she could come too.
It’s another confusing sentence that can, luckily, be fixed with a single comma. Try this:
I invited Joe, and Alice asked if she could come too. CORRECT
So here’s the rule: Use a comma when you join two sentences with and. (Sentences with but work the same way.)
And here’s the underlying principle: Your brain uses that comma to figure out that the first sentence is finished and a new one is beginning.
Let’s try one more example – an and sentence that doesn’t need a comma:
I invited Joe and Alice to the party this weekend. CORRECT
There’s no need to separate “Joe and Alice” – they’re both invited. So I didn’t insert a comma.
Are you surprised how easy this rule is? I am too. Isn’t English wonderful?