that vs. which

Use that at the beginning of a clause that’s necessary for the sentence to make sense. Don’t put a comma before that.

Global tip Include that even if the sentence is clear without it. It helps to clarify the sentence structure.

Use which at the beginning of a clause that adds supporting or parenthetical information. If you can omit the clause and the sentence still makes sense, use which, and put a comma before it.

Examples
To learn more about features that aren’t supported in the trial version, see the feature comparison chart.
Catch the latest episode of “This Week on Windows,” which looks at the new Surface Book and more.
The comparison chart shows which features aren't supported in the trial version.

Don’t use that or which in clauses that refer to a person. Use who instead.

See also who vs. that