Where do we use 'which' and 'that'?

shilpasharma"This is a famous idiom, which means.."
or
"This is a famous idiom that means.."

Both are possible.

CJ

Additional details: I don't just want to know about which one of these two(which and that) will be used in this given sentence, rather I want to know where do we use these two in English. Is there any rules for where to use which and where to use that.

shilpasharmarules for where to use which and where to use that.

Many, many rules. That is too much to put in a forum post! You'll need a book for that. Or you can try Googling 'relative clause'. You will probably be able to find many different sites that explain all the different ways you can use those words. It may take you several days to read them all!

relative clause is the subject that i have difficulty in learning

a Good question

I too have another question like Previous Question

and it's :

is "That" Always used instead "Which" and "who" and "whom" ?

i was also confuse about which and that and what i got is
it`s about restrictive and non-restrictive clause
Use "that" with restrictive clauses and Use "which" with non-restrictive clauses.
regarding your question
"This is a famous idiom, that means YOU are talented person"

"This is a famous idiom, which means talented person"
you can use both but the fact is