To Separate Items in a List:

Use commas to separate three or more items in a series.

Example: I bought apples, oranges, and bananas.

Before Conjunctions in Compound Sentences:

Use a comma before conjunctions (for, and, nor, but, or, yet, so) when they join two independent clauses.

Example: I wanted to go for a walk, but it started raining.

After Introductory Elements:

Use a comma after introductory words, phrases, or clauses.

Example: After the movie, we went out for dinner.

To Set Off Non-Essential Clauses:

Use commas to set off non-essential information that can be removed without changing the meaning of the sentence.

Example: My brother, who lives in New York, is visiting us this weekend.

With Adjectives of Equal Rank:

Use commas between adjectives that equally describe a noun.

Example: It was a long, tiring day.

In Dates, Addresses, Titles, and Numbers:

Use commas to separate elements in dates, addresses, titles, and long numbers.

Example: She was born on May 5, 1999, in Paris, France.

Example: The population of the city is 1,000,000.

Where to Remove Commas

Between Subject and Verb:

Do not use a comma between the subject and the verb of a sentence.

Incorrect: My friend, is coming over.

Correct: My friend is coming over.

With Essential Clauses:

Do not use commas to set off essential information that is crucial to the meaning of the sentence.

Incorrect: The students, who study hard, get good grades.

Correct: The students who study hard get good grades.

Before Dependent Clauses at the End:

Do not use a comma before a dependent clause that comes at the end of a sentence.

Incorrect: She will call you, when she arrives.

Correct: She will call you when she arrives.

Between Adjectives that Are Not Equal:

Do not use a comma between adjectives that do not equally describe a noun.

Incorrect: She wore a bright, red dress.

Correct: She wore a bright red dress.

Examples to Practice

List of Items:

Incorrect: We need to buy milk eggs and bread.

Correct: We need to buy milk, eggs, and bread.

Compound Sentence:

Incorrect: She loves painting and he loves drawing.

Correct: She loves painting, and he loves drawing.

Introductory Element:

Incorrect: Before the show started we found our seats.

Correct: Before the show started, we found our seats.

Non-Essential Clause:

Incorrect: My sister who lives in Boston is a doctor.

Correct: My sister, who lives in Boston, is a doctor.

Equal Adjectives:

Incorrect: It was a hot summer day.

Correct: It was a hot, summer day.

Essential Clause:

Incorrect: The book, that I borrowed from you, is interesting.

Correct: The book that I borrowed from you is interesting.