Which vs. That

When to use which and that

• Use ‘that’ when you are referring to an object belonging to a group/set.
• Use ‘which’ when you are referring to an object that exists on its own.

Let’s look at an example.

By using that in sentence A, we are stating that Tom subscribed specifically to the PhoneVerification API that is available in the API store but there are other PhoneVerification APIs that are available in other locations as well.

In sentence B, we used which to state that Tom subscribed to the only PhoneVerification API available. The fact that it is available in the API store is some extra information for the reader.

Let’s learn more about that vs. which.

When to use ‘that’

We can use ‘that’ with a restrictive clause, which is also known as an essential clause.

Let’s look at a few more examples

When to use ‘which’

We can use which with a nonrestrictive clause, which is also known as a nonessential clause.

Let’s look at a few more examples

When to use the comma

• Do not use a comma before ‘that’ in a sentence that has a restrictive clause.
• Use a comma before ‘which’ in a sentence that has a nonrestrictive clause.
• Do not use ‘that’ or ‘which’ when you are referring to a person. Instead, use ‘who’ and commas to indicate whether it is essential or nonessential information.

Summary

Reference

• Writing Fundamentals Guide
• https://www.grammarly.com/blog/which-vs-that/