Finally I can get some rest after so many busy weeks, which reminds me, I should really do a v2 of Kigurumikku v3 2 and 3.
Let us begin, then.
There are many ways to use a comma, but I’ll just work with what people usually get wrong. Also, I will try to keep the information clear instead of going all technical.
1) Separate an incomplete, dependant sentence (clause) from a complete, independent one.
While I got dressed, the radio was playing a great song.
On that night, we became friends.
We have mustard in our car, of course.
As you may have noticed, everything after the comma makes sense on its own, while everything that precedes the comma does not. Also, this are pretty simple sentences, though they should do the trick.
Knowing when to use the comma is easy, knowing when not to use it is not:
A woman frightened by a mouse bought a cat.
Most people would put ”frightened by a mouse” between commas even though it is wrong. Here, ”woman” is nonspecific, so what follows is essential because we need to know which woman is doing what.
To make it clearer:
The vegetables that people often leave uneaten are usually the most nutritious.
Broccoli, which people often leave uneaten, is very nutritious.
Since we now are talking about a specific vegetable, the clarification is not needed and should go between commas.
Another when not:
The war lasted for two years but it never gathered much support.
Most of the time ”but” is preceded by a comma, but when there are two coordinating conjunctions (for and but in this case) and they separate one incomplete sentence do not us a comma.
2) To separate items in a simple list: Simple being they keyword here.
Apples and oranges.
Apples,oranges, and bananas.
If the list is at least three items long, use a comma before ”and.”
I am sure most people know to separate items in a list with commas, but they do not know they should only do so with simple lists. I will talk about how to separate items in a complex list in another post.
I have merged several specific rules, but this will certainly make it easier for you to learn how to properly use the comma. Also, there are some minor variations to some of the rules, but you should not worry about that yet.
Hope this helps.