As one begins to write academically, it is possible to encounter commonly confused words. A good example of a pair is “that” and “which.” It is important to know the difference between these two words because they mean different things even though they seem to have the same grammatical function. Not using them correctly can affect the quality of your writing. In academic writing, it is essential to be clear and precise to effectively communicate your ideas.
Definition of “that vs. which”
The words “that” and “which” both function as relative pronouns in English, but they are used in different types of relative clauses and carry different connotations. “That” is typically used as a conjunction in restrictive relative clauses, which provide essential information about the noun they modify. These clauses are crucial for the meaning of the sentence, and omitting them would change the sentence’s meaning.
On the other hand, “which” is commonly used in non-restrictive relative clauses, which give additional, non-essential information about the noun. This information is supplementary and can be omitted without altering the fundamental meaning of the sentence.
That
… is a pronoun & conjunction used for essential information in a sentence.
Which
… is a pronoun that is used for additional, non-essential information in a sentence.
Differentiating between “that” and “which” primarily involves understanding the type of information they introduce in a sentence. Use “that” when introducing essential information necessary to understand the sentence’s meaning, as in defining or restrictive clauses. Conversely, use “which” for additional, non-essential information, often set off by commas, as in non-defining or non-restrictive clauses. You can easily remember this by thinking of “which” as a sandwich wrapper. The wrapping is disposable and does not change anything about the sandwich, as well as the clause with “which.”
Note: Use “that” for necessary details and “which” for additional, optional information.
Using the word “that”
The word “that” has several grammatical functions in the English language. “That” is a pronoun, referring to a specific thing and a conjunction, introducing subordinate clauses.
“That” as a pronoun
As a pronoun, “that” is used to refer to a specific thing previously mentioned or understood from the context. Below are example sentences illustrating its usage. In each of these sentences, “that” refers back to a specific item or idea mentioned earlier.
Examples
- I read the book, and that was very fascinating.
- She offered me a cookie, but I declined that.
- We saw the movie last night. That was really good.
“That” as a conjunction
As a conjunction, “that” is used to introduce a subordinate clause, often expressing a reason, result, or explanation. Here are three examples illustrating its usage. In these sentences, “that” introduces clauses that provide further information about the statements made in the main clauses.
Examples
- She said that she would be late.
- I believe that honesty is important.
- He was so tired that he fell asleep immediately.
“That” with essential information
“That” introduces essential or restrictive clauses, meaning the information following “that” is necessary for the meaning of the sentence. Removing this clause would change the overall meaning or make the sentence unclear. Essential clauses do not have commas surrounding them.
Examples
- The car that won the race is on display at the museum.
- The restaurant that serves vegan pizza is closed today.
- She only buys products that are environmentally friendly.
Tip for using “that” correctly
There are few synonyms of “that” that can be used in the same grammatical way as “that” is used. However, in some sentences, “that” can be omitted, and the meaning remains the same.
| Synonyms | Examples |
| So | He was so tired that he fell asleep immediately. |
| “That” can simply be omitted | He was so tired so he fell asleep immediately. |
| The one | I prefer that you showed me yesterday. |
| Used as a pronoun to refer to a specific thing | I prefer the one you showed me yesterday. |
| Who | The person that called earlier left a message. |
| Used for people instead of things or ideas | The person who called earlier left a message. |
Note: “That” can also be changed to “who,” “when,” or “where.” Use “who” for a person, “when” for a time, and “where” for “that place.”
Using the word “which”
“Which” is commonly used as a relative pronoun to refer to a specific part of a sentence, typically in the form of a relative clause, providing additional information about a noun or a noun phrase mentioned earlier. It helps to create a link between the main clause and the relative clause, adding detail or clarification. This use of “which” is common in descriptive phrases, where it serves to provide additional information about the subject or object of the sentence.
“Which” can also function as an interrogative pronoun when asking about specific options or choices within a group. It helps seek information or clarification about a particular selection from among several options.
“Which” as a pronoun
As a pronoun, “which” is used to refer to a specific thing or things previously mentioned or implied in the context, typically in relative clauses. Below are example sentences illustrating its usage. In each of these sentences, “which” refers back to something previously mentioned or understood, helping to form a relative clause that provides further information.
Examples
- I can’t decide which to choose.
- She didn’t know which was more alarming.
- He showed me several paintings, one of which was quite valuable.
“Which” with non-essential information
“Which” introduces non-essential or non-restrictive clauses, which provide additional, but not crucial, information about a noun. This information can be omitted without altering the fundamental meaning of the sentence. Non-essential clauses are usually set off by commas.
Examples
- The painting, which was completed in 1821, is now worth millions.
- Her bike, which she bought last year, was stolen yesterday.
- The book, which I found in the attic, turned out to be a rare first edition.
Tip for using “which” correctly
Strategically using synonyms of “which” enhances writing and speech by preventing repetition and redundancy, ensuring precision, improving clarity, suiting the audience and tone, and fulfilling specific stylistic preferences. Different words carry subtle nuances, making your message more engaging and tailored to the specific context or desired emphasis.
| Synonyms | Examples |
| The one that | The book, which was on the table. |
| The book, the one that was on the table. | |
| What | Which book do you want? |
| What book do you want? | |
| Whichever | Choose which option suits you best. |
| Choose whichever option suits you best. |
Test yourself!
Practice sheet
To improve your ability to differentiate between “that” and “which,” fill in the blanks in the practice sentences. The correct answers can be found in the second tab.
- The book ___ I left on the table is gone.
- She can’t remember the name of the restaurant ___ we visited last week.
- He couldn’t decide ___ shirt to wear for the interview.
- He missed the train ___ would have taken him to the city.
- The car, ___ is over ten years old, still runs perfectly.
- That’s the movie ___ won the award for best picture.
- She showed me several photographs, one of ___ was taken in Paris.
- They found the keys ___ they had lost.
- The story ___ he told us was quite unbelievable.
- She has a collection of rare stamps, ___ includes a Penny Black.
- The book that I left on the table is gone.
- She can’t remember the name of the restaurant that we visited last week.
- He couldn’t decide which shirt to wear for the interview.
- He missed the train that would have taken him to the city.
- The car, which is over ten years old, still runs perfectly.
- That’s the movie that won the award for best picture.
- She showed me several photographs, one of which was taken in Paris.
- They found the keys that they had lost.
- The story that he told us was quite unbelievable.
- She has a collection of rare stamps, which includes a Penny Black.
in Your Thesis
FAQs
The choice between “that” and “which” often depends on the type of relative clause you’re dealing with: restrictive or non-restrictive.
- Use “that” for restrictive clauses
- Use “which” for non-restrictive clauses
Both “which” and “that” are used in British English, but there are some differences in their usage compared to American English, particularly in formal writing.
In everyday, informal speech and writing, the distinction between “which” and “that” is often blurred in both varieties of English, and they can be used interchangeably.
“Which” is normally used in English in two primary contexts:
- Non-restrictive relative clauses
- Interrogative sentences
In both these uses, “which” serves to add information or inquire about something specific from a known group or set. The usage is consistent across different forms of English, including both British and American English.
Using “that” should be avoided in a few specific contexts:
- Non-restrictive clauses
- After prepositions
- In formal writing
Remember, “that” is best used in restrictive clauses, where the information it introduces is essential to the meaning of the sentence and no commas are used.
In a sentence, “that” and “which” are used to introduce relative clauses, but they serve different purposes and follow different rules.
Examples
- The book that I lost is irreplaceable
- The book, which I bought yesterday, is on the table.
