That vs. Which

‘That’ or ‘which’?

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:

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

E.g. 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):

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

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