Use of Comma

Use of Comma

1. Use a comma after a dependent clause:

If a sentence starts with a dependent clause, you need to put a comma before writing an independent clause to finish the sentence. (Just like this sentence)
Example:
If you don't drink enough water, your kidneys will function poorly. 

There is no need to use the comma if the sentence starts with an independent clause. (Just like this sentence too!)

Example:

Your kidneys will function poorly if you don't drink enough water.

2. Use commas to separate an appositive from a sentence

Depending on the position of an appositive in a sentence, you need to put one or more commas after and before the appositive.

Appositive at the Begining:
My best friend, Almas came to visit me.
Appositive at the Middle:
Almas, my best friend, came to visit me.
Appositive at the End:
The man who came yesterday is Almas, my best friend.

If you write the direct speech after mentioning the speaker, put a comma after the verb of the speaker(say, ask, add, reply, etc.) and before the first quotation mark:

Nobita said, "Can you please help me?"


If you write the direct speech at the beginning of a sentence, the comma should be placed before the final quotation mark. It will be wrong if you use a full stop instead of a comma. 

"Yes, but don't ask anything stupid," Doraemon replied. 

If you split a direct speech into two and write the speeches before and after mentioning the speaker, you need to use two commas: one after the first part(inside the quotation mark) and another before the second part(before the quotation mark):

"Yes," Doraemon replied, "but don't ask anything stupid."

[Observe that only one sentence was split or broken into two, so 'but' started with a small letter after "Doraemon replied, "]

If the direct speech which is at the beginning of a sentence ends with a question mark(?) or an exclamation mark(!), do not replace them with a comma, and do not add a comma. For example, 

"Can you please help me?" Nobita said.