Using Which, That, and Who

The words which, that, and who are all relative pronouns. This means they relate groups of words to other nouns or pronouns. In the examples below, click on the relative pronoun to find out which word or group of words each one relates to.

I have never been to Dakar, which is reputed to be very beautiful. [Which relates to “Dakar.”]

The books that hold the greatest appeal are not the ones recommended by our teacher. [That relates to “the books.”]

I would like to speak with the consultant who wrote this report.

Determining when to use that and which to introduce a clause depends on whether the clause is essential to the reader's comprehension of the sentence. As a result, using that and which correctly can reduce possible misinterpretations of meaning.

Which

When a clause is descriptive or parenthetical and could be removed from the sentence without changing the sentence’s meaning, use which and enclose the clause with commas.

The Environmental Policy Report, which Elena introduced at yesterday's meeting, is under review.

Because “the Environmental Policy Report” is the name of a specific report, the reader knows which report the sentence is referring to. The clause “which Elena introduced at yesterday's meeting” is simply additional information. Therefore, which should be used. The clause “which Elena introduced at yesterday’s meeting” is not essential to the reader's understanding of the noun.

That

When a clause serves to limit or define the noun it is modifying, use that to introduce the clause.

The report that Elena introduced at yesterday's meeting is under review.

Without the clause “that Elena introduced at yesterday's meeting,” the reader will not know which report the sentence is referring to. The likelihood for misinterpretation by the reader is great. Therefore, that should be used. Also, because the clause is essential to the sentence's construction, there should be no commas.