Comma Rules Made Simple: 8 Essential Rules Every Writer Needs

Commas are the most frequently misused punctuation mark. These eight rules cover the most important comma situations you'll encounter.

1. Before Coordinating Conjunctions in Compound Sentences

"I write every day, and my skills are improving."

2. After Introductory Elements

"However, the results were unexpected." "After finishing dinner, we went for a walk."

3. In Lists (Oxford Comma)

"I packed books, snacks, and water." The Oxford comma (before "and") prevents ambiguity.

4. Around Nonessential Information

"My sister, who lives in Boston, is visiting." (The clause adds extra info but isn't essential to identify which sister.)

5. Between Coordinate Adjectives

"She wore a long, elegant dress." (Test: Can you put "and" between them? If yes, use a comma.)

6. Before Direct Quotes

She said, "Grammar matters."

7. In Dates and Addresses

"On January 5, 2026, we launched." "New York, New York"

8. To Prevent Misreading

"Let's eat, Grandma." (Without the comma: "Let's eat Grandma." Very different meaning!)

Our grammar checker catches comma errors automatically and explains the rule behind each correction.