The most misused punctuation mark in the English language is the comma. As a secondary school teacher, I used to bang my head against the wall trying to teach commas. Personally, I just don’t like the slippery little suckers. If I can get away without using a comma, I don’t use one. Oxford commas can just go and jump as far as I’m concerned unless they’re absolutely necessary. My number one rule for people who are uncertain about their comma usage is: ask yourself if you really need a comma. The instances where you really should use one are listed below:
To Separate Subordinate Causes from Main Clauses
I used to explain this to the kids by saying that you separate the bit of the sentence that wouldn’t make sense without the rest of it. Yeah, it’s technically more complicated than that but let’s not get confusing.
Look at the following sentence and see which part could be used on its own and which part couldn’t:
Because of their soft fur and independent natures, cats are my favourite animals.
I could even put the bit that doesn’t make sense on its own in the middle of the sentence.
Cats, because of their soft fur and independent natures, are my favourite animals.
In that instance, the subordinate clause needs commas at both ends.
The only time you don’t generally need a comma is when the main clause comes first:
Cats are my favourite animals because of their fur and independent natures.
‘Bits’? You’re thinking. I could have put ‘vocatives’, ‘adverbials’ and ‘discourse markers’ but that sort of thing puts people right off. It’s much more friendly and simple to think of these ‘add ons’ to sentences as ‘bits’. Here are some examples of ‘bits’ that need commas to separate them from the main part of the sentence:
Well, that could’ve gone better.
Actually, he makes a good point.
She did really well there, don’t you think?
On Tuesday, it will rain.
People generally know you use commas to separate items on a list but it gets confusing when the Oxford comma comes into it. Whether you use it or not is entirely up to you. I don’t like to use it unless it’s confusing not to. I had to write a list of government departments recently and the number of them that included an ‘and’ meant that an Oxford comma was necessary.
When not to Use a Comma
A constant source of frustration for me was the kids I taught using commas where they should have used full stops. I often saw things like this:
I like Christmas, this is because I get lots of presents.
Never use a comma before ‘this’. It should have either been two sentences:
I like Christmas. This is because I get lots of presents.
Or one sentence with no comma and no ‘this’:
I like Christmas because I get lots of presents.
You don’t generally need to use a comma before ‘and’ (except for the occasional Oxford comma) or ‘but’. There are some circumstances where they are appropriate here but, as a rule, you don’t normally need one.
These are very rough rules for using commas. My English teacher colleagues and fellow writers would probably disagree with me but these basic guidelines should suffice for general business writing.