Table of Contents
Quick Overview
Understanding the difference between Which and That is essential for clear, professional writing in American English. These two words are classic homophones-they sound almost identical in everyday speech, but they have completely different meanings and grammatical functions. Mixing them up is one of the most common spelling and grammar mistakes in the English language.
| Feature | Which | That |
|---|---|---|
| Meaning | Asks for a choice, or introduces non-essential (non-restrictive) information | Points out a specific item, or introduces essential (restrictive) information |
| Part of Speech | Interrogative or Relative Pronoun / Determiner | Demonstrative or Relative Pronoun / Conjunction |
| Pronunciation | /wɪtʃ/ | /ðæt/ |
| Common Contexts | Questions, non-restrictive clauses set off by commas | Restrictive clauses without commas, pointing out objects, reported speech |
| Example | The car, which is red, is fast. | The car that is red is fast. |
| Memory Trick | Which = Comma (extra info) | That = Tight (essential info, no commas) |
Understanding "Which"
A detailed breakdown of meaning, grammar, and usage.
Meaning
Pronunciation
Word Class (Pronoun / Determiner)
Grammar
Common Uses
Literal Meaning
Figurative Meaning
American English Usage
Typical Sentence Patterns
Common Collocations
Understanding "That"
A detailed breakdown of meaning, grammar, and usage.
Meaning
Pronunciation
Word Class (Pronoun / Conjunction / Determiner)
Grammar
Common Uses
Literal Meaning
Figurative Meaning
American English Usage
Typical Sentence Patterns
Common Collocations
Key Differences
Core Definition
Which introduces non-essential (extra) information or asks a question. That introduces essential (defining) information or points out an object.
Punctuation
Which is typically preceded by a comma in relative clauses. That is never preceded by a comma in relative clauses.
Part of Speech
Which is strictly a pronoun or determiner. That can be a pronoun, determiner, or conjunction.
Directionality
Which focuses on specifying a choice among many. That focuses on restricting a category to a specific item.
Comparison Table
| Feature | Which | That |
|---|---|---|
| Meaning | Asks for a choice, or introduces non-essential (non-restrictive) information | Points out a specific item, or introduces essential (restrictive) information |
| Part of Speech | Interrogative or Relative Pronoun / Determiner | Demonstrative or Relative Pronoun / Conjunction |
| Pronunciation | /wɪtʃ/ | /ðæt/ |
| Common Contexts | Questions, non-restrictive clauses set off by commas | Restrictive clauses without commas, pointing out objects, reported speech |
| Example | The car, which is red, is fast. | The car that is red is fast. |
| Memory Trick | Which = Comma (extra info) | That = Tight (essential info, no commas) |
Grammar Rules
Grammar Rules & Mechanics
The distinction between 'which' and 'that' is one of the most common grammatical debates in American English. Mastering restrictive vs. non-restrictive clauses is the key.
Restrictive vs. Non-Restrictive Clauses
'That' is used for restrictive clauses (essential to the meaning). 'Which' is used for non-restrictive clauses (extra, non-essential info).
- Correct: The car that is red is mine. (Essential: tells you exactly which car)
- Incorrect: The car, which is red, is mine. (Non-essential: you already know which car is mine)
If removing the clause changes the sentence's core meaning, use 'that'. If it just adds bonus info, use 'which' with commas.
The Comma Rule
Commas dictate the pronoun choice. If you need a comma before the relative pronoun, use 'which'. If you don't, use 'that'.
- Correct: The report, which was fifty pages long, took weeks to write.
- Incorrect: The report, that was fifty pages long, took weeks to write.
Never use a comma immediately before 'that' in a relative clause. 'Which' is the correct choice for non-restrictive clauses.
Referring to People
Both 'that' and 'which' refer to things. However, 'that' can also refer to people in restrictive clauses, while 'which' cannot.
- Correct: The man that called you is my uncle.
- Incorrect: The man which called you is my uncle.
Use 'that' or 'who' for people. 'Which' is strictly for inanimate objects or animals.
That as a Conjunction
'That' can function as a subordinating conjunction to introduce reported speech or thoughts. 'Which' cannot do this.
- Correct: She said that she would be late.
- Incorrect: She said which she would be late.
Use 'that' to connect a reporting verb (said, thought) to the clause being reported.
When to Use "Which"
Specific scenarios where 'which' is the correct choice. It is used to ask questions, offer choices, or introduce non-essential information in a relative clause.
Asking Questions
Use 'which' when asking someone to choose from a limited, known set of options.
Example: Which flavor of ice cream do you want?
Non-Essential Clauses
Use 'which' to add extra information that is not strictly necessary to identify the noun. These clauses are set off by commas.
Example: My house, which has a red door, is at the end of the street.
Offering Choices
Use 'which' as a determiner before a noun to offer a specific selection.
Example: Which shirt looks better on me?
Referring to Objects
In relative clauses, 'which' is traditionally used to refer to things or animals, not people.
Example: The laptop, which I bought yesterday, is already broken.
Referring to Whole Ideas
Use 'which' to refer back to an entire preceding clause or sentence.
Example: He failed the test, which is unfortunate.
Indicating a Preference
Use 'which' in statements comparing known options.
Example: I don't know which is better.
Formal Writing
In formal American English, 'which' is strictly reserved for non-restrictive (comma) clauses.
Example: The report, which was due Friday, arrived late.
Prepositional Objects
When a preposition precedes the relative pronoun, use 'which' (e.g., in which, of which).
Example: The box in which the ring was stored is missing.
When to Use "That"
Specific scenarios where 'that' is the correct choice. It is used to point out specific items, introduce essential information, or connect clauses.
Essential Clauses
Use 'that' to introduce information that is strictly necessary to identify the noun. Do not use commas.
Example: The car that is red belongs to me.
Pointing Out Objects
Use 'that' as a demonstrative pronoun to indicate a specific object far from the speaker.
Example: I want that book on the top shelf.
Reported Speech
Use 'that' as a conjunction to introduce reported speech or thoughts.
Example: She said that she would be late.
Referring to People or Things
In essential relative clauses, 'that' can refer to both people and things.
Example: The man that called you is my uncle.
Demonstrating Distance
Use 'that' to contrast physical or conceptual distance (this vs. that).
Example: This pen is mine; that one is yours.
Connecting Results
Use 'that' in phrases like 'so that' or 'such that' to show purpose or outcome.
Example: He spoke loudly so that everyone could hear.
Informal Omission
In informal speech, 'that' can sometimes be omitted when it is the object of a relative clause.
Example: The book (that) I read was fantastic.
Emphasizing a Quality
Use 'that' to emphasize a specific trait or degree (e.g., that good).
Example: I didn't think it was that difficult.
Common Expressions
Idioms and standard phrases that rely on the specific meaning of each word.
Expressions with "Which"
1. Which one
Meaning: Asking to specify a single item from a known group.
Example: Which one of these ties matches my suit?
2. Which way
Meaning: Asking for a direction or path.
Example: Which way is the nearest gas station?
3. Which of
Meaning: Selecting from a specific subset of items or people.
Example: Which of these applicants has the most experience?
4. Which is why
Meaning: Introducing a consequence or reason based on a previous fact.
Example: It was raining, which is why I took an umbrella.
5. Which means
Meaning: Clarifying or defining what a previous statement implies.
Example: The bridge is closed, which means we have to take a detour.
6. In which
Meaning: Formal prepositional structure indicating location or context.
Example: The box in which the ring was stored is missing.
7. Which color
Meaning: Asking to specify a shade or hue.
Example: Which color looks best for the living room walls?
8. Which time
Meaning: Asking to specify a particular hour or appointment.
Example: Which time works better for you, 2 PM or 4 PM?
9. Which day
Meaning: Asking to specify a day of the week.
Example: Which day are we scheduled to leave for vacation?
10. Which is which
Meaning: Asking how to distinguish between two similar items.
Example: The twins look so alike I can't tell which is which.
11. Every which way
Meaning: An idiom meaning in all directions or completely disorganized.
Example: The papers scattered every which way when the fan hit them.
12. Any which way
Meaning: An idiom meaning in any manner or direction.
Example: You can arrange the furniture any which way you like.
13. Don't know which way to turn
Meaning: An idiom expressing extreme confusion or lack of options.
Example: After losing his job and his home, he didn't know which way to turn.
14. Which came first
Meaning: A phrase used when discussing cause and effect or chronology.
Example: It's a chicken-and-egg scenario; which came first, the stress or the insomnia?
15. Know which side your bread is buttered
Meaning: An idiom meaning knowing what is best for oneself.
Example: He won't argue with the boss; he knows which side his bread is buttered on.
16. Which is to say
Meaning: A phrase used to clarify or rephrase a previous statement.
Example: He is a pedant, which is to say he focuses too much on tiny details.
17. At which point
Meaning: Indicating the exact moment an action occurred.
Example: The alarm rang, at which point the dog started barking.
18. For which
Meaning: Prepositional structure indicating reason or purpose.
Example: The reasons for which he was fired remain confidential.
19. Of which
Meaning: Prepositional structure indicating possession or composition.
Example: He bought a dozen eggs, three of which were broken.
20. Which implies
Meaning: Indicating a logical conclusion drawn from a fact.
Example: The data shows a decline, which implies a shift in consumer habits.
Expressions with "That"
1. That one
Meaning: Pointing out a specific item, often contrasted with 'this one'.
Example: I don't want this pen; I want that one.
2. The fact that
Meaning: A common introductory phrase for a subordinate clause.
Example: The fact that he showed up late is unacceptable.
3. So that
Meaning: A conjunction phrase used to show purpose or intention.
Example: Please speak loudly so that everyone can hear you.
4. Now that
Meaning: A conjunction phrase meaning 'because' or 'since' something has happened.
Example: Now that it is raining, we should go inside.
5. That said
Meaning: A transitional phrase meaning 'despite what was just said'.
Example: The project was difficult. That said, we finished it on time.
6. Such that
Meaning: A formal phrase meaning 'to the extent that' or 'so that'.
Example: The pressure was such that the pipe burst.
7. Provided that
Meaning: A conditional phrase meaning 'on the condition that'.
Example: You can borrow the car provided that you fill the gas tank.
8. That is to say
Meaning: A phrase used to clarify or explain a previous statement.
Example: He is a perfectionist; that is to say, he expects flawless work.
9. Not all that
Meaning: An informal phrase meaning 'not very' or 'not exceptionally'.
Example: The movie was not all that good.
10. In that
Meaning: A formal phrase meaning 'because' or 'for the reason that'.
Example: The new policy is better in that it offers more flexibility.
11. For all that
Meaning: A phrase meaning 'despite' or 'in spite of'.
Example: For all that he complained, he still ate the entire meal.
12. And all that
Meaning: An informal phrase meaning 'and similar things'.
Example: We had a great vacation with swimming, sunbathing, and all that.
13. That'll be the day
Meaning: An idiom expressing strong skepticism that something will happen.
Example: He says he'll clean his room without being asked? That'll be the day!
14. That's that
Meaning: An idiom meaning a decision is final and no more discussion is needed.
Example: You are grounded, and that's that.
15. The car that
Meaning: Standard restrictive clause modifying an inanimate object.
Example: The car that I rented broke down on the highway.
16. The person that
Meaning: Standard restrictive clause modifying a person.
Example: The person that called you left a message.
17. The reason that
Meaning: Introducing the cause or justification for something.
Example: The reason that I am late is the traffic.
18. Except that
Meaning: A phrase used to introduce an exception or caveat.
Example: I would buy the house, except that the roof is leaking.
19. That much
Meaning: Indicating a specific, often limited, degree or quantity.
Example: I don't like spicy food that much.
20. That way
Meaning: Pointing out a specific manner, direction, or method.
Example: If you study hard, you will pass the test that way.
Collocations
Which one
Meaning: Asking to specify a single item.
Example: Which one of these is your favorite?
Which way
Meaning: Asking for direction.
Example: Which way did the dog run?
Which of
Meaning: Selecting from a group.
Example: Which of these fruits is ripe?
Which is why
Meaning: Introducing a reason or consequence.
Example: I forgot my wallet, which is why I couldn't pay.
Which means
Meaning: Clarifying an implication.
Example: The store is closed, which means we have to go elsewhere.
In which
Meaning: Formal prepositional phrase for location or context.
Example: The environment in which we work is stressful.
Of which
Meaning: Indicating composition or possession.
Example: He owns three cars, two of which are convertibles.
For which
Meaning: Indicating purpose or reason.
Example: The award for which he was nominated is prestigious.
At which
Meaning: Indicating a specific time or point.
Example: The meeting, at which the merger was discussed, was long.
Which color
Meaning: Asking to specify a shade.
Example: Which color should I paint the front door?
The fact that
Meaning: Introducing a factual subordinate clause.
Example: The fact that she apologized shows maturity.
So that
Meaning: Conjunction showing purpose.
Example: Save your money so that you can buy a house.
Now that
Meaning: Conjunction meaning 'since' or 'because'.
Example: Now that spring is here, the flowers are blooming.
That one
Meaning: Pointing out a specific item.
Example: I don't like this shirt; I prefer that one.
That said
Meaning: Transition meaning 'despite that'.
Example: The food was expensive. That said, it was delicious.
Provided that
Meaning: Conditional phrase.
Example: You can go out provided that your homework is done.
Except that
Meaning: Introducing a caveat.
Example: The plan is perfect except that it costs too much.
Such that
Meaning: To the extent that.
Example: His anger was such that he couldn't speak.
In that
Meaning: Because; for the reason that.
Example: This computer is better in that it has more memory.
That way
Meaning: In that manner or direction.
Example: Turn left and go that way for two miles.
Idioms
Which is which
Meaning: How to distinguish between two identical or similar things.
Example: The twins look so alike that I can't tell which is which.
Every which way
Meaning: In all directions; completely disorganized.
Example: The toys were scattered every which way across the room.
Any which way
Meaning: In any manner or direction; haphazardly.
Example: You can arrange the chairs any which way you prefer.
Know which way the wind blows
Meaning: To understand the current trends or how a situation is developing.
Example: He knows which way the wind blows and is voting accordingly.
Don't know which way to turn
Meaning: To be completely lost, confused, or without options.
Example: After the sudden bankruptcy, she didn't know which way to turn.
Which came first, the chicken or the egg
Meaning: A paradox regarding cause and effect.
Example: We are arguing about which came first, the chicken or the egg.
Know which side your bread is buttered
Meaning: To know what is advantageous for oneself.
Example: He won't argue with his boss; he knows which side his bread is buttered.
Which is to say
Meaning: In other words; meaning.
Example: The train is delayed, which is to say we will be late.
Go whichever way
Meaning: To proceed in any chosen direction or manner.
Example: The decision can go whichever way the committee votes.
Look which way
Meaning: To see in what direction something is moving or developing.
Example: Investors are watching to look which way the market turns.
That's that
Meaning: A decision is final, and there is nothing more to say.
Example: I won't buy the car, and that's that.
That'll be the day
Meaning: An expression of strong skepticism that something will ever happen.
Example: He says he'll wake up early to jog? That'll be the day!
That said
Meaning: However; despite what was just said.
Example: The hotel was expensive. That said, the service was excellent.
Not all that
Meaning: Not very; not exceptionally good or impressive.
Example: Everyone loved the movie, but I thought it was not all that.
And all that
Meaning: And other similar things; et cetera.
Example: We had a nice dinner with wine, dessert, and all that.
For all that
Meaning: In spite of everything; despite.
Example: For all that he studied, he still failed the exam.
In that
Meaning: For the reason that; because.
Example: This phone is superior in that it has a better camera.
That much
Meaning: To that extent or degree.
Example: I didn't realize you cared about the issue that much.
So that
Meaning: In order that; with the result that.
Example: Leave early so that you miss the rush hour traffic.
Now that
Meaning: Since; because something has happened.
Example: Now that you are 18, you can vote.
Example Sentences
Easy
- Which shirt do you want to wear?
- I want that red ball.
- The book that I read was good.
- My dog, which is brown, is sleeping.
- Which way is the park?
- She said that she is happy.
- The car that is fast is mine.
- I don't know which one to choose.
- That is a very big house.
- The cat, which is black, meowed.
- Which color do you like best?
- I think that it will rain today.
- The toy that broke is in the trash.
- This pen is mine; that one is yours.
- The tree, which is very old, fell down.
- Which day are we going to the beach?
- He hopes that he will win the game.
- The apple that I ate was sweet.
- Which of these cakes looks tasty?
- That movie was really scary.
Intermediate
- The laptop, which I bought last year, is already obsolete.
- The laptop that I bought last year is already obsolete.
- She couldn't decide which dress to wear to the party.
- The manager said that the meeting was rescheduled.
- The house that has the red door is for sale.
- The house, which has a red door, is for sale.
- I need to know which route is the fastest.
- He finished the race, which is an amazing accomplishment.
- The fact that he lied is very disappointing.
- Please speak louder so that everyone can hear.
- The contract that we signed expires next month.
- The contract, which was fifty pages long, took hours to review.
- Which of these candidates has the most experience?
- That is the reason I am leaving the company.
- The storm, which lasted all night, caused severe flooding.
- Now that the rain has stopped, we can go for a walk.
- The car that broke down on the highway was finally towed.
- He forgot his keys, which means he is locked out.
- I didn't realize the project was that complicated.
- The book that you lent me was fascinating.
Advanced
- The research paper, which was published in a top-tier journal, has been cited hundreds of times.
- The research paper that was published in a top-tier journal has been cited hundreds of times.
- The CEO announced that the company would undergo a massive restructuring.
- The paradigm that governs modern physics is based on relativity.
- The findings, which contradict previous studies, suggest a new mechanism.
- The committee must determine which course of action is most prudent.
- The fact that the experiment failed demonstrates the theory's limitations.
- He is a brilliant scholar, which is widely acknowledged in academic circles.
- The legislation that was passed last year is now facing judicial review.
- The team, which has struggled all season, fired its head coach.
- She argued that the policy was inherently flawed.
- The protocol that governs data encryption has been updated.
- The symphony, which was composed in the 19th century, remains timeless.
- Investors are unsure which way the market will turn next quarter.
- That said, the overall economic outlook remains cautiously optimistic.
- The artifact that was discovered in the tomb dates back to 3000 BCE.
- The climate, which has been erratic recently, is affecting agriculture.
- The hypothesis that the researcher proposed has been validated.
- The novel, which is considered a masterpiece, won multiple awards.
- It is evident that the current strategy is no longer viable.
Academic
- The methodology, which is outlined in section three, ensures reproducibility.
- The methodology that was employed in this study ensures reproducibility.
- The researcher posited that the control group would show no variance.
- The variable that controls the outcome is temperature.
- The empirical data, which was collected over a decade, supports the thesis.
- The survey indicates which factors influence consumer behavior.
- The fact that the results were statistically significant validates the hypothesis.
- The framework, which integrates multiple disciplines, offers a holistic view.
- The theorem that the mathematician proved revolutionized the field.
- The experiment, which was conducted in a vacuum, yielded precise measurements.
- The author argues that linguistic drift is inevitable.
- The text that was analyzed dates back to the Middle Ages.
- The archives, which contain rare manuscripts, are restricted to scholars.
- The model demonstrates which parameters are most sensitive to change.
- It is clear that further research is required to confirm these findings.
- The chemical reaction that occurs at high temperatures is exothermic.
- The historical context, which is often overlooked, is crucial for understanding.
- The professor emphasized that academic integrity is paramount.
- The algorithm that processes the data has been optimized.
- The sample size, which was deemed sufficient, prevented anomalies.
Business
- The Q3 report, which was released yesterday, exceeded expectations.
- The report that was released yesterday exceeded expectations.
- The CEO announced that the merger would be finalized next week.
- The client that generates the most revenue is demanding a discount.
- The office, which is located downtown, is easily accessible.
- We need to determine which vendor offers the best pricing.
- The fact that the deadline was missed resulted in a penalty.
- The software, which was custom-built, integrates seamlessly.
- The employee that was hired last month is already leading a project.
- Please review the contract so that we can proceed with the signing.
- The product that launched last quarter is our best-seller.
- The marketing campaign, which cost two million dollars, increased sales.
- We must decide which strategy to pursue for the upcoming year.
- That said, we cannot ignore the risks associated with this venture.
- The supplier that we used last year went out of business.
- The new policy, which takes effect immediately, applies to all staff.
- The manager confirmed that the budget was approved.
- The factory that produces our components is overseas.
- The acquisition, which was heavily debated, is now complete.
- It is essential that we maintain client confidentiality.
Real-Life Conversations
Office
Colleague 1: Did you read the email that the boss sent?
Colleague 2: Yes, the one about the new policy, which starts next week.
Colleague 1: Exactly. Which department do you think will be affected the most?
Colleague 2: I think HR will struggle, given that they manage all the files.
Retail
Customer: Excuse me, which aisle has the coffee?
Cashier: It is in aisle four, right next to that display of mugs.
Customer: Perfect. I also need to find the sugar that is organic.
Cashier: That would be in the baking section, which is just past the dairy.
School
Student: Which book did the professor assign for homework?
Teacher: The textbook that we reviewed in class today.
Student: Oh, the one with the blue cover, which has the historical timelines?
Teacher: Yes, that is the correct book. Please read chapter four.
Travel
Passenger: Which terminal is my flight departing from?
Agent: Your flight leaves from Terminal B, which is a short walk from here.
Passenger: Great, I hope that the security line isn't too long.
Formal vs Informal Usage
Professional Emails
In professional writing, 'that' defines essential project details, while 'which' adds supplementary information in comma-separated clauses.
Example: The proposal that you submitted was excellent. The appendices, which were attached, provided extra context.
Legal Writing
Legal documents use 'that' to define strict conditions and 'which' to provide clarifying, non-binding context.
Example: The party that breaches the contract must pay a fine, which is non-refundable.
Business English
Contracts and Agreements
In contracts, 'that' restricts obligations to specific parties, while 'which' offers descriptive background.
Example: The vendor that supplies the materials is reliable. The delivery schedule, which is flexible, suits us.
Meeting Minutes
Meeting minutes use 'which' to note outcomes and 'that' to assign specific action items.
Example: It was decided that the budget would be cut, which surprised the marketing team.
Academic Writing
Research Papers
In academic papers, 'that' connects a theory to its essential evidence, while 'which' adds parenthetical methodology notes.
Example: The enzyme that catalyzes the reaction was isolated, which confirms previous hypotheses.
Literature Studies
Literary analysis uses 'which' to offer commentary on quotes and 'that' to identify specific texts.
Example: The poem that we analyzed is complex, which is evident in its shifting metaphors.
Common Mistakes
The car, that is red, is mine.
Correct: The car, which is red, is mine.
Why: Never use a comma before 'that' in a relative clause. Use 'which' for non-essential info.
The book which I read was good.
Correct: The book that I read was good.
Why: In American English, use 'that' for essential (restrictive) clauses without commas.
I don't know that one to pick.
Correct: I don't know which one to pick.
Why: Use 'which' when asking for a choice between known options.
He said which he would be late.
Correct: He said that he would be late.
Why: Use 'that' as a conjunction for reported speech, not 'which'.
The man which called you is here.
Correct: The man that called you is here.
Why: 'Which' cannot refer to people. Use 'that' or 'who' for people.
The laptop, which I bought is broken.
Correct: The laptop that I bought is broken.
Why: The clause is essential to identify the laptop, so no commas should be used, requiring 'that'.
She doesn't know which way to turn.
Correct: She doesn't know which way to turn.
Why: This sentence is correct. 'Which way' is the proper phrase for asking direction.
The fact which he lied is troubling.
Correct: The fact that he lied is troubling.
Why: In the phrase 'the fact that', always use 'that' as the conjunction.
The house that has a red door, is for sale.
Correct: The house that has a red door is for sale.
Why: Do not put a comma between a noun and an essential 'that' clause.
This is the box in that the ring was stored.
Correct: This is the box in which the ring was stored.
Why: After a preposition (in, of, for), use 'which', never 'that'.
Learning Tips
Memory Trick: Which = Comma
Notice that 'Which' and 'Comma' both contain the letter 'C'. If the clause needs a comma, use 'which'.
Memory Trick: That = Tight
'That' starts with 'T', like 'Tight'. It binds the essential information tightly to the noun, with no commas allowed.
The Removal Test
If you can remove the clause and the sentence still means the same thing (just with less detail), use 'which' with commas. If the meaning changes or becomes unclear, use 'that'.
The Choice Rule
If you are asking a question about choosing between items, always use 'which' (Which color?). 'That' cannot ask a question.
The Preposition Rule
If a preposition comes right before the relative pronoun (e.g., 'in', 'of', 'for'), you must use 'which'. You can never end a preposition with 'that'.
🎮 Mini Quiz
Test your knowledge with these interactive questions.
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Frequently Asked Questions
Quick answers to common questions.
What is the main difference between which and that?
'Which' is used for non-essential, extra information and is set off by commas. 'That' is used for essential, defining information and does not use commas.
Can 'which' and 'that' be used interchangeably?
In British English, they are sometimes used interchangeably, but in American English, the rule is strict: 'that' for essential clauses, 'which' for non-essential.
Is it 'the car which is red' or 'the car that is red'?
If you are using the color to identify the specific car out of a group, use 'that' (the car that is red). If you already know the car and are just describing it, use 'which' (the car, which is red).
Can 'that' refer to people?
Yes, in restrictive clauses, 'that' can refer to people (The boy that hit me). However, 'who' is often preferred for people, while 'which' cannot refer to people at all.
Can 'which' refer to an entire sentence?
Yes, 'which' can refer to the whole preceding clause (e.g., He won the race, which is amazing). 'That' cannot do this.
How do you pronounce which and that?
'Which' is pronounced /wɪtʃ/ (starting with a 'w'). 'That' is pronounced /ðæt/ (starting with a 'th').
Is it 'the fact that' or 'the fact which'?
It is 'the fact that'. 'That' functions as a conjunction here, which 'which' cannot do.
Can 'that' be used in questions?
No, 'that' cannot be used to ask questions. Only 'which' can (e.g., Which one?).
Do 'which' and 'that' share the same etymology?
No. 'Which' comes from Old English 'hwilc'. 'That' comes from Old English 'þæt'. They have always been distinct words.
What happens if I use a comma before 'that'?
It is grammatically incorrect in standard English. A comma before a relative pronoun indicates a non-restrictive clause, which requires 'which', not 'that'.
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