Commas are among the most misused punctuation marks in English. They have specific rules for lists, clauses, introductory phrases, and more. Both missing commas and unnecessary commas change the rhythm and sometimes the meaning of a sentence.
Use commas to separate items in a list of three or more. "She bought apples, oranges, and bananas." The comma before "and" at the end of a list is called the Oxford (or serial) comma. In British English it is often omitted; in American English it is usually kept. When the last two items could be confused without it, the Oxford comma is essential: "I'd like to thank my parents, Einstein, and Newton" vs. "my parents, Einstein and Newton" (which implies your parents are Einstein and Newton).
Practice
Which sentence is correctly punctuated?
The report covered marketingsales, and customer service.
Put the words in the correct order with correct punctuation:
Use a comma after an introductory subordinate clause that comes before the main clause: "Although it was late, she stayed to finish the work." No comma is needed when the subordinate clause comes second: "She stayed to finish the work although it was late." For non-defining relative clauses, commas are required on both sides: "My brother, who lives in Berlin, is visiting next week."
Practice
Which sentence is correctly punctuated?
My colleaguewho has worked here for 20 years
Put the words in the correct order:
Use a comma + coordinating conjunction (for, and, nor, but, or, yet, so — FANBOYS) to join two independent clauses: "She studied hard, and she passed." Without the conjunction, a comma alone creates a comma splice error: "She studied hard, she passed." ✗ — use a period, semicolon, or add a conjunction. A comma splice is one of the most common writing errors.
Practice
Which sentence contains a comma splice (an error)?
I wanted to comeI had too much work.
Fix the comma splice — put in the correct order: