That, which and who
Use who for people, that for essential details about things, and which (with commas) for extra details.
Updated October 29, 2026
The rule
Refer to people with who: the girl who won, not the girl that won (in formal writing) and never the girl which won.
That introduces a detail you need to know which one (the car that broke down) and takes no commas. Which introduces an extra detail and follows a comma (my car, which is red, broke down).
Examples
The teacher which helped me retired.The teacher who helped me retired.The house, that we sold, was old.The house, which we sold, was old.
Quick test: People get who. For things, a comma before it means which; no comma means that.
Try it: find the mistake
The mistake in each sentence is highlighted. Say the fix out loud, then open the answer.
The girl which sits next to me is funny.
The girl who sits next to me is funny.
Use who for people.
The bike that I rode, is in the garage.
The bike that I rode is in the garage.
This tells which bike, so it is essential and takes no comma before "is".
My house, that has a red door, is on the corner.
My house, which has a red door, is on the corner.
An extra detail set off by commas takes which, not that.
The players that won the tournament were honored at the assembly.
The players who won the tournament were honored at the assembly.
Players are people, so formal writing uses who.
Where this rule is tested
Questions people ask
What is the rule for that, which and who?
Use who for people, that for essential details about things, and which (with commas) for extra details. Refer to people with who: the girl who won, not the girl that won (in formal writing) and never the girl which won.
How can I check my that, which and who quickly?
People get who. For things, a comma before it means which; no comma means that.
Where can I practice this for free?
In Owl Test Prep's Daily Grammar Fix: one sentence a day for everyone, plus practice sets of five on this rule. It is free, with no account.