When it comes to English grammar, many learners often get confused between “that” and “which”. Both words are used to introduce clauses in sentences, but their meanings and usage are different.
Choosing the wrong word can make a sentence unclear or grammatically incorrect. Understanding the correct usage of that or which is essential for clear and professional writing.
In this article, we will break down the differences between that and which, provide simple explanations, examples, and tips. By the end, you’ll be able to confidently use these words in your writing and speech.
Quick Answer
Use “that” for clauses that are essential to the meaning of the sentence (restrictive clauses), and use “which” for clauses that add extra, non-essential information (non-restrictive clauses) and are usually set off by commas.
Meaning and Definition of Each Word
1. That
Definition: “That” is a relative pronoun used to introduce essential information in a sentence.
Explanation: The clause introduced by that is necessary to understand the sentence correctly. Removing it may change the meaning.
Example Sentences:
- The book that I borrowed is excellent.
- She likes the dress that is red.
2. Which
Definition: “Which” is a relative pronoun used to introduce additional, non-essential information.
Explanation: The clause introduced by which can be removed without changing the main meaning of the sentence. It is usually separated by commas.
Example Sentences:
- The book, which I borrowed yesterday, is excellent.
- She wore a dress, which was bright red.
Key Differences Between “That” and “Which”
- Essential vs Non-Essential:
- That → Essential information (restrictive)
- Which → Extra information (non-restrictive)
- That → Essential information (restrictive)
- Commas:
- That → No commas
- Which → Usually preceded by a comma
- That → No commas
- Sentence Meaning:
- That → Removing it changes the sentence meaning
- Which → Removing it doesn’t change the main idea
- That → Removing it changes the sentence meaning
- Formal Writing:
- That → Commonly used in both formal and informal writing
- Which → Often used in formal writing with commas
- That → Commonly used in both formal and informal writing
Comparison Table
| Word | Meaning | Usage | Example |
| That | Essential/restrictive information | Introduces clauses needed for sentence | The car that is parked outside is mine. |
| Which | Non-essential/additional info | Introduces clauses set off by commas | My car, which is parked outside, is mine. |
Examples in Sentences
Using That
- The movie that we watched last night was thrilling.
- I need the report that John submitted.
- The house that has a red door is mine.
Using Which
- The movie, which we watched last night, was thrilling.
- I need the report, which John submitted yesterday, for my meeting.
- The house, which has a red door, belongs to my friend.
Common Mistakes
- Incorrect: I like the phone, that has a big screen.
- Correct: I like the phone that has a big screen.
- Incorrect: The pen that I bought, is very expensive.
- Correct: The pen, which I bought, is very expensive.
Tip: Always check if the clause is essential to the sentence. If yes, use that; if no, use which.
Tips to Remember the Difference
- Think about necessity: Ask yourself, “Do I need this clause to identify the noun?” → If yes, use that.
- Look for commas: Clauses with commas are usually which clauses.
- Use memory trick: “That is a must; which is extra.”
- Read aloud: The sentence will often sound natural if the correct word is used.
When to Use Each Word
Use That:
- Identifying a specific item: The cake that she baked was delicious.
- When the clause is essential for clarity: Students that study hard will pass the exam.
Use Which:
- Adding extra information: The cake, which she baked yesterday, was delicious.
- Giving a side note or detail: He wore a jacket, which was too big for him.
Grammar Rules
- Restrictive Clauses (That): No commas, necessary for meaning.
- Non-Restrictive Clauses (Which): Use commas to separate from the main clause.
- Position: Both words usually follow the noun they describe.
Examples:
- Restrictive: The students that arrive late cannot enter.
- Non-Restrictive: The students, which arrived late, had to wait outside. (Note: “which” with people is rare; “who” is more common.)
Synonyms or Related Words
- For that → who (for people), whom, whichever
- For which → whatever, whichever, who (for people in non-restrictive clauses)
Frequently Asked Questions (FAQs)
- Can we use “which” instead of “that”?
Yes, but only in non-essential clauses. Using it in essential clauses can be incorrect. - Do we always need a comma with “which”?
Yes, in non-restrictive clauses, a comma is necessary. - Can “that” be used for people?
Yes, e.g., The teacher that teaches math is kind. But “who” is more natural. - Is “which” formal English?
Yes, “which” with commas is preferred in formal writing. - How can I remember the difference?
Remember: “That is necessary, which is optional.” - Can “that” start a sentence?
Usually not. It follows a noun or pronoun it describes.
Conclusion
Understanding the difference between that or which is simple once you remember the essential rule: “that” for necessary information, which “which” for extra information.” Using these words correctly improves clarity and makes your writing sound professional. Practice identifying essential and non-essential clauses, and soon it will become second nature.
