|Relative pronouns: choosing between who, which, that|
|Does the clause affect the meaning?
||Defining (= essential information)
||Undefining (= additional information)
|Can the pronoun be omitted?
||Yes, if it is the object.
# the book you're reading
# the man I love
|Is it a person?
# I don't like people who (that) are always loud.
# My sister, who lives in Madrid, is coming for the weekend.
|Is it an animal/a thing?
# The song which (that) you wrote is very beautiful.
# The Azores, which lie 1400 away from Lisbon, are a perfect holiday destination.