Dear All,
I've a question. I need to know when to use 'that' and when to use 'which' in a sentence.

As per what i've read so far, 'which' can come after ',' or preposition. I'm really not sure about the other usages.

Somewhere i've read that 'which' is used for a restrictive clause or something like that. Please someone throw light on this topic.

Thanks in Advance.