Mastering the Use of Which and That in English Grammar

By Strategically AI. Reviewed by Rebecca Hey.
Updated January 18, 2024
3 minute read
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Navigating the intricacies of English grammar can sometimes feel like walking through a linguistic labyrinth. Among the most common points of confusion is the use of "which" and "that." While they might seem interchangeable, these two words have distinct roles in sentences. In this article, we'll explore the correct usage of "which" and "that," providing clarity with examples to help you use them confidently in your writing and conversations.

Understanding the Difference Between Which and That

The key to distinguishing between "which" and "that" lies in understanding their grammatical roles and the context in which they are used.

The Role of 'That'

"That" is used to introduce essential clauses, also known as restrictive clauses. These clauses are crucial to the meaning of a sentence because they define or identify the subject being talked about.


  • The book that I borrowed last week is fascinating.

The Function of 'Which'

"Which," on the other hand, introduces non-essential clauses, also known as non-restrictive or parenthetical clauses. These clauses provide additional information about the subject but are not crucial to the sentence's meaning.


  • The book, which I borrowed last week, is fascinating.

Navigating Usage in Sentences

Understanding when and how to use "which" and "that" can significantly impact the clarity of your writing.

In Descriptive Contexts:

  • Use "that" to specify which thing or group you are talking about.
  • Use "which" to add non-essential information to a sentence.

In Formal Writing:

  • The distinction between "which" and "that" is particularly important in formal writing, where precision and clarity are key.

Summary and Key Insights

Remember, "that" is for essential information, and "which" is for additional details. Keeping this distinction in mind will help you navigate their usage with ease.

Frequently Asked Questions

Can "which" and "that" be used interchangeably?

In informal speech, they are often used interchangeably, but for formal writing, it's important to use them correctly as per their grammatical roles.

How do I decide whether to use "which" or "that"?

Ask yourself if the clause you're writing is essential to the meaning of the sentence. If it is, use "that." If it's just additional information, use "which."

Do I always need to use a comma before "which"?

Yes, when "which" introduces a non-essential clause, it should be preceded by a comma.

Can "that" be omitted in a sentence?

In some cases, "that" can be omitted if the sentence is clear without it. However, omitting "which" can lead to confusion.

Is this distinction observed in British English as well?

Yes, the distinction between "which" and "that" is observed in both British and American English, especially in formal writing.


Mastering the use of "which" and "that" is a subtle yet powerful tool in enhancing your English language skills. Understanding the nuances of their usage not only improves your communication but also reflects a deeper appreciation of the language's complexity.

If you're aiming to refine your writing with precision and clarity, our expert content writing agency at Strategically offers SEO content, unlimited revisions, and more. Let us help you navigate the intricacies of English for impactful and error-free writing.

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Rebecca Hey
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