Many English learners and even native speakers often feel confused about using “which or that.” At first glance, both words seem similar because they are used to give extra information about something. But in reality, they are used in different ways, and choosing the wrong one can sometimes change the meaning of a sentence.
People search for “which or that” because they want to improve their grammar and write more clearly. You’re writing an essay, email, or blog post, using the correct word helps your message sound more professional and easy to understand.
In this article, you will learn the difference between “which” and “that” in the simplest way possible. We will explain meanings, rules, examples, common mistakes, and easy tips so you can use both words correctly and confidently.
Quick Answer
“That” is used for essential information (important to the meaning of the sentence), while “which” is used for extra information (not necessary for the sentence to make sense).
Also, “which” is usually used with commas, while “that” is not.
Meaning and Definition of Each Word
What is “That”?
Definition:
“That” is used to give essential information about a noun. This information is necessary to understand the sentence.
Simple Explanation:
If you remove the part with “that,” the sentence may lose its meaning.
Examples:
- The book that is on the table is mine.
- I like movies that make me laugh.
- She bought a dress that fits perfectly.
What is “Which”?
Definition:
“Which” is used to give extra (non-essential) information about a noun.
Simple Explanation:
If you remove the part with “which,” the sentence still makes sense.
Examples:
- The book, which is on the table, is mine.
- My car, which is very old, still works.
- She bought a dress, which looks beautiful.
Key Differences Between “Which” and “That”
Here are the main differences explained in a simple way:
- Importance of Information:
- “That” → Important (essential)
- “Which” → Extra (non-essential)
- Use of Commas:
- “That” → No commas
- “Which” → Uses commas
- Sentence Meaning:
- “That” → Defines exactly which thing you mean
- “Which” → Adds extra details
- Removal Test:
- “That” → Cannot remove (meaning changes)
- “Which” → Can remove (meaning stays clear)
Comparison Table
| Word | Meaning | Usage | Example |
| That | Essential information | No commas | The phone that I bought is expensive. |
| Which | Extra information | Used with commas | The phone, which I bought yesterday, is new. |
Examples in Sentences
Using “That”
- The cake that she baked tastes amazing.
- I need a pen that works properly.
- The house that we saw yesterday is beautiful.
- He is looking for a job that pays well.
- The dog that barked last night belongs to my neighbor.
Using “Which”
- The cake, which she baked yesterday, tastes amazing.
- My pen, which is blue, is missing.
- The house, which we saw yesterday, is expensive.
- His car, which is very fast, won the race.
- The dog, which barked last night, woke everyone up.
Common Mistakes
Many learners make mistakes when using “which or that.” Let’s look at some common ones.
1. Using “Which” Without Commas
❌ Incorrect:
The book which is on the table is mine.
✅ Correct:
The book that is on the table is mine.
OR
The book, which is on the table, is mine.
2. Using “That” With Commas
❌ Incorrect:
The car, that I bought, is red.
✅ Correct:
The car that I bought is red.
OR
The car, which I bought, is red.
3. Mixing Up Essential and Extra Information
❌ Incorrect:
My brother which lives in London is a doctor.
✅ Correct:
My brother, which lives in London, is a doctor. (Better: “who”)
OR
My brother that lives in London is a doctor. (if identifying)
4. Overusing “Which”
Some people use “which” everywhere.
❌ Incorrect:
I have a friend which helps me.
✅ Correct:
I have a friend that helps me.
Tips to Remember the Difference
Here are some easy tricks to help you remember:
1. Use the “Comma Rule”
- If there is a comma → use “which”
- If there is no comma → use “that”
2. Ask Yourself: Is It Important?
- Important → use “that”
- Extra → use “which”
3. The Removal Test
- Remove the clause:
- If sentence still makes sense → use “which”
- If meaning is lost → use “that”
4. Think of “That” as a Filter
“That” helps you identify something specific.
Example:
- The shirt that is blue (not the red one)
When to Use Each Word
Use “That” When:
- You are giving necessary information
- You are identifying something specific
- No commas are used
Examples:
- The student that studies hard will succeed.
- The phone that I lost was expensive.
Use “Which” When:
- You are giving extra information
- The sentence is already clear without it
- You use commas
Examples:
- My phone, which I bought last year, still works.
- The movie, which was very long, was interesting.
Grammar Rules for “Which or That”
1. Relative Clauses
Both “which” and “that” are used in relative clauses (they describe nouns).
- “That” → Restrictive clause (important)
- “Which” → Non-restrictive clause (extra)
2. Comma Usage
- Non-restrictive clauses (which) → commas required
- Restrictive clauses (that) → no commas
3. Formal vs Informal Writing
- In formal writing, the difference between “which or that” is important.
- In informal speech, people sometimes mix them, but it’s better to use them correctly.
4. Using “Which” for Things
“Which” is usually used for objects, not people.
Example:
- The car, which is red, is mine.
5. Avoid Using “That” After a Comma
❌ The book, that I read, was good.
✅ The book, which I read, was good.
Synonyms or Related Words
Here are some related words you may see:
- Who → used for people
Example: The man who called me is my uncle. - Whose → shows possession
Example: The girl whose bag is lost is crying. - Where → used for places
Example: The place where we met is special. - When → used for time
Example: The day when we met was beautiful.
Frequently Asked Questions (FAQs)
1. Can I use “which” instead of “that”?
Sometimes yes, but not always.
Use “that” for essential information and “which” for extra information.
2. Is it wrong to use “which” without a comma?
In formal grammar, yes. “Which” should usually be used with commas.
3. Can I remove a “which” clause?
Yes. A “which” clause gives extra information, so it can be removed without changing the main meaning.
4. Why is “that” more common in defining clauses?
Because it clearly identifies which specific thing you are talking about.
5. Is “that” used for people?
Sometimes in informal English, but “who” is preferred for people.
6. Which is more formal: “which” or “that”?
Both are correct, but “which” is often used more in formal writing when adding extra information.
Conclusion
Understanding the difference between “which or that” is very important for clear and correct English. Remember the simple rule: use “that” for important information and “which” for extra details. Also, don’t forget the comma rule “which” needs commas, but “that” does not.
With practice and the tips shared in this article, you can easily master the use of these words. Keep practicing by reading and writing sentences, and soon it will feel natural to choose the right one.
