Choosing between that and which can be a challenge, even for native English speakers. Both words introduce clauses that give more information about a noun, but they are not always interchangeable. Understanding the difference between restrictive and nonrestrictive clauses is essential for using that and which correctly. These small words play a big role in sentence clarity, precision, and meaning. Knowing when to use that versus which can enhance both your writing and speaking, especially in formal contexts.
Understanding Restrictive Clauses
A restrictive clause, also known as a defining clause, provides essential information about the noun it follows. Without this clause, the sentence’s meaning would change significantly or become unclear. In American English, restrictive clauses are typically introduced with that, and no comma is used before the clause.
Examples of Restrictive Clauses with That
- The bookthat has a red coveris mine.
- She adopted the dogthat was abandoned at the shelter.
In both examples, the clause beginning with that is crucial. Without it, the reader wouldn’t know which book or which dog is being talked about. The word that restricts or defines the noun more precisely.
Key Features of Restrictive Clauses
- Essential to the meaning of the sentence
- No commas used
- Commonly introduced with that
Understanding Nonrestrictive Clauses
A nonrestrictive clause, also called a non-defining clause, adds extra information about a noun that is already clear or specific. This information is helpful but not essential to the core meaning of the sentence. Nonrestrictive clauses are typically introduced with which and are set off by commas.
Examples of Nonrestrictive Clauses with Which
- The car,which is parked outside, belongs to my uncle.
- My laptop,which I bought last year, is already outdated.
Here, the clauses provide additional, non-essential information. You could remove the clause, and the sentence would still make sense. The commas signal to the reader that the clause is just extra detail.
Key Features of Nonrestrictive Clauses
- Not essential to the main meaning
- Set off with commas
- Typically introduced with which
That vs. Which The Grammar Rule
In American English, the general rule is
- Usethatfor restrictive clauses (no comma)
- Usewhichfor nonrestrictive clauses (with comma)
This rule helps make writing more precise and readable. While British English is often more flexible, American English tends to enforce this distinction more strictly, especially in academic or professional settings.
Example Comparison
- RestrictiveThe moviethat won the awardwas fantastic. (Specifies which movie)
- NonrestrictiveThe movie,which won the award, was fantastic. (Adds extra info about a known movie)
The first sentence limits the subject to a specific movie. The second assumes the reader already knows the movie and simply adds more information about it.
Why the Distinction Matters
Understanding the difference between that and which in restrictive and nonrestrictive clauses is more than just a grammar technicality. It affects the meaning of sentences. Misusing them can lead to confusion or unintended ambiguity.
Clarity in Communication
Using that and which correctly ensures that your reader or listener gets the right message. It helps distinguish whether information is vital or optional.
Professional Writing and Editing
Editors and style guides, like those used in journalism or publishing, often insist on using that for restrictive clauses and which for nonrestrictive ones. Following this convention improves consistency and readability.
Common Mistakes and How to Avoid Them
Many writers overuse which even in restrictive clauses. To avoid this, ask yourself Can the sentence stand without the clause? If yes, use which with commas. If not, use that without commas.
Incorrect Example
The carwhich is redbelongs to her. (Incorrect if more than one car is being referred to.)
Corrected Version
The carthat is redbelongs to her.
Or, if the car is already identified
The car,which is red, belongs to her.
Exceptions and Flexibility
While the rule is useful, it’s important to note that
- In British English, which can be used in restrictive clauses (but usually still without a comma).
- In informal writing or speech, the rule may not always be followed strictly.
- Some style guides allow flexibility depending on tone and clarity.
However, in formal, academic, or business English especially in the U.S. it’s best to follow the that for restrictive and which for nonrestrictive rule.
Quiz Yourself
Try identifying whether the following clauses are restrictive or nonrestrictive, and which word should be used
- The documents ___ were missing have been found.
- The Empire State Building, ___ is in New York, is famous worldwide.
- The students ___ study hard usually pass the exam.
- My sister, ___ lives in Paris, sent me a gift.
Answers
- that(Restrictive)
- which(Nonrestrictive)
- that(Restrictive)
- which(Nonrestrictive)
Tips for Mastery
- When in doubt, remove the clause. If the sentence still makes sense, it’s nonrestrictive use which.
- Remember No comma for that; commas for which.
- Check your writing for consistency and follow your preferred style guide.
- Practice by editing sentences and applying the rules until they become second nature.
Understanding how to use that and which correctly comes down to identifying whether the clause is restrictive or nonrestrictive. That introduces essential information, while which adds extra details. Being aware of this distinction improves clarity, reduces ambiguity, and enhances the professionalism of your writing. Whether you’re writing essays, topics, reports, or emails, applying the right rule ensures your message is both correct and effective. Once you master the rules of restrictive vs. nonrestrictive clauses, your writing will reflect greater control and precision.