1. Yes, there ARE specific rules!
Commas

2. Rule 1: Two independent clauses linked by a conjunction need a comma.
Tom wanted to buy a pizza, but he didn’t have any money. (for, and, nor, but, or, yet, so)

3. Rule 2:Use in lists and include a comma before the conjunction.
I bought apples, tomatoes, and carrots. (3+)

4. Rule 3: Use in a list of just two items.
John is a smart, happy man. (2+)

5. Rule 4: Dependent clause before an independent clause, use a comma after the dependent clause.
Unless you are going, I won’t go.

6. Rule 5:Adjective clause
Lucy, who is a tall woman, climbed a tree. (extra information, adjective clause)

7. Rule 6: Direct quote
Mark said, “I want some candy”.

8. Rule 7:Getting someone’s attention
Racing, John, is a very popular sport.

9. Rule 8:Before a Transition word.
Suzie didn’t study. Therefore, she didn’t pass. (however, consequently)

10. Which of the following is correct?
I like cars, music and computers. I like cars, music, and computers. I like cars, music, and, computers. I like cars, music and, computers

11. Answer:
I like cars, music, and computers.

12. Which of the following is correct?
Mr. Jones who, likes to travel, is on vacation in India. Mr. Jones who likes to travel, is on vacation in India. Mr. Jones, who likes to travel, is on vacation in India. Mr. Jones who likes to travel is on vacation, in India.

13. Answer:
Mr. Jones, who likes to travel, is on vacation in India.

14. Which of the following is correct?
You Steven, need to pay more attention in class. You, Steven, need to pay more attention in class. You Steven need to pay more attention, in class. You Steven, need to pay more attention, in class.

15. Answer: You, Steven, need to pay more attention in class.
In this case, you are trying to get Steven's attention, and place a comma before and after his name to emphasize that you are addressing him.

16. Which of the following is correct?
I was feeling very hungry, so I went to the store to buy some food. I, was feeling very hungry, so I went to the store to buy some food. I was feeling very hungry so, I went to the store to buy some food. I was feeling very hungry, so, I went to the store to buy some food.

17. Answer:
I was feeling very hungry, so I went to the store to buy some food.

18. Which of the following is correct?
Because it was raining I stayed home and watched television. Because, it was raining, I stayed home and watched television. Because it was raining, I stayed home and watched television. Because it was raining, I stayed home, and watched television.

19. Answer: Because it was raining, I stayed home and watched television.
This is a case of a dependent clause coming before an independent clause. To link the two, we must use a comma between each clause

20. Which of the following is correct?
John is tall, dark, and handsome.
John is tall, dark and handsome.
John is tall dark, and handsome
John is tall dark and handsome.

21. Answer:
John is tall, dark, and handsome.