Difference Between Which and That
Most of us may be surprised to know about the difference in usage of that and which because we hardly bother to differentiate them before using them. Simply explained, that is to be sued when you want to add additional information about something which is talked about in the sentence earlier while which is used for adding additional information which may not be necessary.
‘That’ is used for adding restrictive relative clauses while ‘which’ for non-restrictive relative clauses. Relative Clause is that part of a sentence which relates the information with the person or subject being talked about. Relative Clause is either restrictive or non-restrictive. That and Which are replaced by ‘who’ when we talk about people.
Let us understand these concepts with some examples.
- It is the shop that sells newspaper.
- He is the person who sells newspaper.
We can see difference and how ‘who’ has replaced ‘that’ when we talked about a person. Here the second half of the sentence tells s about the shop or the person who sell newspaper. This provides the information about the shop and the person we are talking about, hence it is relative clause.
Now understanding the usage of which and that with examples:
- Roger needs a book that is written by John Denny.
Here we observe following facts:
- After using that we have added additional information which is essential for others to know because it specifies and gives you information about the particular book needed by Roger.
- The clause is added by using ‘that’ to provide essential information.
- We do not use comma while using ’that’.
- Here the clause is added but it does not provide any essential information about the noun in the first half of the sentence.
- We use comma while adding such clause.
- Roger needs a book, which he likes.
The easiest way to remember is if you want to add essential information without adding comma then use ‘that’ else use ‘which’. Ask yourself if the information is essential or not.