These are main comma rules, but one should note that rules for direct address, clarity, interjections, addresses, dates, and numbers do exist. These rules cover those commas that separate items and those that join items.
Rule 1: Separating Items in a Series
Use a comma to separate items in a list of three or more.
Examples: America’s landscape is composed of deserts, mountains, plains, and forests.
The astronauts’ mission was to land on Mars, take soil samples, and come back safely.
Notice that the items in a series, whether nouns, verbs, or clauses, must remain parallel, meaning that all of the items in that series must be nouns.
Rule 2: Separating Introductory Elements from the Main Clause
Use a comma to separate an introductory word or clause from the independent clause.
Examples: After three years of intense therapy, I was able to write again.
Today, I will call my friend.
Although the terms of the contract were unclear, no one disputed it.
Therefore, you need a comma.
Rule 3: Separating Coordinating Adjectives
Use a comma between coordinating adjectives. You can tell coordinating adjectives by inserting the word “and” between them and switching their order. If they still make sense, they are coordinating and require a comma.
Examples: The dry, boring man was elected to office.
The large brown elephant ramped through the streets. No comma is necessary because “large” is modifying the type of elephant (brown).
Rule 4: Separating Non-Restrictive Elements
Use a comma to set off nonessential clauses and information.
Examples: The people, who do not bathe, are my neighbors.
The people who do not bathe are my neighbors.
In the first case, none of my neighbors bathe. In the second example, only those people identified as those who do not bathe are my neighbors.
Example: Jeff, the surly plumber, just quit smoking.
Rule 5: Joining Independent Clauses with a Conjunction
Use a comma with a conjunction (and, but, or, nor, for, yet, so) when joining independent clauses.
Examples: I was going to the store, and I accidentally went in the wrong direction.
The Chicago Bears looked poised to win yet another division, but after their many injuries, they were left with too many losses to even make the playoffs.
Rule 6: Joining a Direct Quote
Use a comma to introduce a direct quotation after expression verbs (says, states, believes, feels, thinks).
Examples: Banks stated, “let’s play two.”
“This is not the end of me,” wrote Sam.
Do not use a comma with an indirect quote; instead, use “that.”
Banks stated that he would like to play two games of baseball.
He felt that the rules were too strict.
Exercise
1. In cases of hurricanes, tornadoes, and cyclones, it is best to hide in the basement, turn off electric equipment and drink bottled water.
In cases, cyclones it equipment, correct as is
2. Ericka and Traci went down to the beach but they forgot their surfboards and were forced to go back home.
Ericka, beach, surfboards, correct as is
3. The people, who live at the end of the block, are noisy.
The people who live at the end of the block are noisy correct as is
4. People, who are also called humans, need food to live.
People who are also called humans need food to live. correct as is
5. Anthony was not in his usual perky self today because of his lack of sleep, his nagging family, and his traffic accident.
Anthony, today, sleep correct as is
6. The nearly indestructible superhero leaped from building to building without damaging the rooftops or his swank fashionable new tights.
nigh, rooftops, swank, correct as is
7. Neither Janice nor Joan knew that their new student lockers would be so near one another.
Janice, knew, new, correct as is
8. While Rupert stated that he needed time to think, Isabella said "Forget you, guy."
stated, think said, correct as is
Answers
1. equipment, (item in a list)
2. beach, (two independent clauses joined by a conjunction)
3. The people who live at the end of the block are noisy (just those people)
4. correct
5. correct
6. swank, (the adjectives can be switched and separated by "and")
7. correct
8. said, (direct quotation after an expression verb)