A period makes a full stop. A semicolon (;) is a softer stop that says “these two belong together.” It joins two independent clauses without a conjunction, the same kind of clauses you joined with a comma and and in Commas in Compound Sentences.
Key idea
Use a semicolon (1) between two closely related independent clauses, (2) before a word like however, therefore or instead that joins two clauses, with a comma after that word, and (3) between items in a list when the items already have commas.
Why it works
The semicolon lets a writer show that two ideas are linked without spelling out how. In a list, it acts as a bigger comma, so the reader can see where each item ends.
Worked example: A list with commas inside
“We visited Akron, Ohio, Boise, Idaho, and Reno, Nevada.”
- Each item is a city and a state, with its own comma inside.
- With commas between the items too, the reader can’t tell where one place ends.
- Use semicolons between the items.
Answer: We visited Akron, Ohio; Boise, Idaho; and Reno, Nevada.
Worked example: Before however
“It rained all morning however the game went on.”
- Two independent clauses: “It rained all morning” and “the game went on.”
- However is not a conjunction, so it can’t join them alone.
- Semicolon before it, comma after it.
Answer: It rained all morning; however, the game went on.
Common mistake
Using a semicolon where a colon or a comma belongs: before a list (“I need three things; flour, eggs and milk”) or after a dependent clause (“Because it rained; we stayed inside”). The test: could you put a period there instead? If not, don’t use a semicolon (unless you are separating list items that contain commas).