Relative pronouns are a type of pronoun that introduce relative clauses within a sentence. These clauses provide additional information about a noun or pronoun mentioned earlier in the sentence and help to connect ideas within a sentence or a larger piece of writing. Relative pronouns include words such as "who," "whom," "whose," "which," and "that." Here is a brief explanation of each relative pronoun:

1. Who/Whom: Used to refer to people. "Who" is used as a subject or a subject complement, while "whom" is used as an object.

Example:

- The woman who lives next door is a doctor.

- I met a man whom I had never seen before.

2. Whose: Used to indicate possession or ownership and is used with both people and things.

Example:

- The book whose cover is torn belongs to me.

- The student whose grades improved received a scholarship.

3. Which: Used to refer to things or animals.

Example:

- The car, which is parked outside, needs to be repaired.

- The dog, which was abandoned, was adopted by a kind family.

4. That: Can be used to refer to both people and things, although it is more commonly used for things. It is often used in restrictive clauses, where the information is essential to the meaning of the sentence.

Example:

- The house that I grew up in has been sold.

- The movie that we watched last night was really interesting.

These relative pronouns help to join relative clauses to the main clause of a sentence and provide additional information or clarification about a person, thing, or idea mentioned earlier.