Comma (,)

It is used:

1- To separate items in a list which is made up of the same parts speech.

e.g. The U.K. consists of England, Wales, Scotland (,) and northern Ireland.

e.g.My new friend is generous pretty(,) intelligent

2- To enclose words used in oppositions:

e.g. Martin Luther King, the peace Nobel Prize winner, was short dead in Atlanta.

e.g. John and Inga, the couple from next door, are coming for dinner tonight.

3- To separate independent clauses in a sentence

e.g. While I was eating, the cat scratched at the door.

4- To separate the words spoken in direct speech from the rest of the sentence.

e.g. My father said, “ I will see you tomorrow”.

e.g. “I was able”, she answered, “to complete the assignment”.

5- Use commas to prevent confusion

e.g. To George, Harisson had been a sort of idol.