THAT and WHICH indicate different things. Do not use them interchangeably.
That
THAT begins a phrase that is essential to the meaning of the word it modifies (it is “restrictive”). The phrase is not set off with commas.
In other words, a comma never precedes the word THAT:
We bought the chair that completes the dining room set.
Which
WHICH begins a phrase that is not essential to the meaning of the word it modifies (it is “nonrestrictive”). The phrase is set off by commas.
In other words, a comma precedes the word WHICH; in addition, you could leave out the entire phrase between the commas and the sentence would still stand on its own:
The new chair, which will be delivered tomorrow, completes the dining room set.
This page has been visited 2008 times.
