When do I use which or that in a sentence?

Question

Someone please tell me the difference between which and that

Answer 1

Let me give you two examples to explain the correct usage of "which" and "that."

1. We recently installed new siding on our house, which was flooded last month.

Use "which" when the information in your subordinate clause ("which was flooded last month") is non-essential to the meaning of the sentence. If you took away the subordinate clause, the reader would still know what house you are referring to.

2. I returned the book that I bought last night.

You should use "that" when the information directly following it is essential to understanding the sentence. Without "that I bought last night," the reader wouldn't know which book you are talking about.

The way I remember it is by thinking of "that" as a tight knot within a sentence and "which" as a looser bow.

Answer 2

Do you sometimes wonder whether to use that or which in a sentence? In many cases, in British English, both words are equally correct.

√ She held out the hand which was hurt.

√ She held out the hand that was hurt.

In these sentences, that and which are introducing what’s known as a restrictive relative clause. This is a clause containing essential information about the noun that comes before it. If you leave out this type of clause, the meaning of the sentence is affected – indeed, it will probably not make much sense at all. Restrictive relative clauses can be introduced by that, which, whose, who, or whom.

The other type of relative clause is known as a non-restrictive relative clause. This kind of clause contains extra information that could be left out of the sentence without affecting the meaning or structure. Non-restrictive clauses can be introduced by which, whose, who, or whom, but you should never use that to introduce them. For example:

A list of contents would have made it easier to steer through the book, which also lacks a map.

She held out her hand, which Rob shook.

Note that a non-restrictive clause is preceded by a comma (so as to set off the extra information), whereas no comma should precede a restrictive clause (indicating that the information is essential, not extra):

I bought a new dress, which I will be wearing to Jo's party. [non-restrictive]

I was wearing the dress that I bought to wear to Jo's party. [restrictive]

Answer 3

When you use "which" in a sentence, it is part of a relative clause, directly modifying the word or words that precede it:

Example: The television series, "Law & Order", which is a popular crime drama, often explains various aspects of the criminal justice system.

Notice the comma that precedes the word "which" in the example. If you took the relative clause, "which is a popular crime drama, the sentence still makes sense.

When you use "that" in a sentence, it is also a modifier, but it is not part of a relative clause. It adds information about the noun it follows.

Example: "Can you please grab the green book that is at the top of the bookcase?"

Notice that no comma is needed in this sentence. The word preceding the phrase, "that is at the top of the bookcase" is the noun "book", to which the word "that" directly refers. It tells us the particular book the speaker is asking someone to grab.

This leads me to the other function of the word "that." When used as a definite article (a modifier), it refers to a specific item.

That magic wand belongs to the sorcerer.

That tire is heavy and hard to carry.

A simple test you can use to determine whether to use "which" or "that" is to check the meaning of the sentence when you take out the clause in question. If the clause points to information that is essential to the meaning of the sentence, then you would use "that". If the clause is used to enhance without taking anything away from the meaning of the sentence, then use "which". Eliminating the relative clause that begins with "which" does take out information, but not knowing that information doesn't affect our understanding of the sentence itself; the clause simply provides more detail about the words it modifies.

Answer 4

Answer 5

When I attended the University of Phoenix, we had a grammar checker called WritePoint.  Whenever I used the word "which" in a sentence, it would make a note explaining in scholarly writing, "that" was preferable to "which," and if "that" could be substituted for "which" without changing the meaning of the sentence, replace "which" with "that." 

Answer 6

Absolutely! Also keep in mind that you don't necessarily always use a comma when using "which", so keep your sentence structures in mind!

Answer 7

I agree with Rebecca and resound with her conclusion that even though it seems random, that and which are consistent in sentences. Simply, if you are doubting the use of that or which... remember that a "a witch is a ditch". (once you understand that, it'll stick!)