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.