comparison
Use which and that with confidence in formal and everyday writing.
Use that for essential clauses and which for nonessential clauses with commas.
Some UK usage is more flexible, but consistency within one style guide matters most.
If the sentence meaning changes without the clause, use that. If the clause is extra detail, use which with commas.
We review each guide for practical usefulness, not just correctness. A good usage guide should give the rule, show the exception, and help a reader make a decision in a real draft.
When examples are available, we connect the article to corpus-backed definitions, synonyms, contrasts, and sentence evidence so the advice is grounded in actual word behavior.
Use this quick matrix to compare core words in this guide and jump directly into deeper lookup pages.
which
And.
that
Something being indicated that is there; one of those.
comma
The punctuation mark ⟨,⟩ used to indicate a set of parts of a sentence or between elements of a list.
clause
A group of words that contains a subject and a verb; it may be part of a sentence or may constitute the whole sentence, depending on the syntax in each instance.
Related words can clarify the boundary of a usage rule. Synonyms show nearby meanings; contrast words help identify what the term does not mean in context.
High-value alternatives
High-value alternatives
Example sentences pulled from our lexical corpus to show natural context.
which
All that which is invented, is true.
that
That was probably what influenced their decision.
comma
In another paragraph, he put in a comma.
clause
The clause provides that all decisions shall be made by majority vote.
Before applying this guide, write the sentence both ways and ask what changes for the reader. If the change only affects surface style, it may not be worth making.
If the change affects meaning, grammar, credibility, or reader trust, use the more precise option and keep a short note for future edits.
Not always in global English, but many US editors prefer that in restrictive clauses.
Yes, but formal writing benefits from clarity here.
Review note: This guide is reviewed by the WordToolSet editorial team for practical usefulness, example quality, and alignment with our editorial standards. Source and data notes are documented on the data sources page, and corrections can be submitted through the corrections workflow.