When to use WHICH and THAT
A clause is a group of words that has both a subject and a predicate. Every complete sentence is made up of at least one clause. With that, if the sentence has a clause but does not need it, use “which” and if the sentence does need the clause, use “that.”
Moreover, we use the word “That” to show a specific thing, object, subject item, or person. For example, “That’s the girl I am talking about” or “That is my book.” We use the word “which” to add information to objects, items, people, and situations. For example, “Sally returned with a cool damp towel which she placed on Lisa’s face and then the back of her neck” or “She mentioned all the details, which was all irrelevant.”
