1. Who, Which and That
When should we use them?

2. Who vs Which Who and sometimes that refer to people.
Examples: Anya is the one who rescued the bird. "The Man That Got Away" is a great song with a grammatical title.
That and which refer to groups or things.
Examples:
John is on the team that won first place. Sarah belongs to a great organization, which specializes in saving endangered species.

3. Which vs That
That introduces what is called an essential clause Essential clauses add information that is vital to the point of the sentence.
Which introduces a nonessential clause which adds supplementary information.
Example: 
I do not trust products that claim "all natural ingredients" because this phrase can mean almost anything.
The product, which claims to use "all natural ingredients" , is on sale now.

4. Now try the quiz below to test your knowledge!