Explain the difference between restrictive and non-restrictive clauses.

Restrictive and non-restrictive clauses are two types of dependent clauses that provide additional information about a noun or pronoun in a sentence. The main difference between these two types of clauses lies in their impact on the meaning and structure of the sentence.

A restrictive clause, also known as an essential or defining clause, is necessary for the sentence to convey its intended meaning. It provides essential information that restricts or limits the meaning of the noun or pronoun it modifies. Restrictive clauses are not set off by commas and are crucial for the sentence's overall meaning. If a restrictive clause is removed, the sentence would lose its intended meaning or become grammatically incorrect.

For example:
- The book that I borrowed from the library is due tomorrow.
In this sentence, the restrictive clause "that I borrowed from the library" is essential to identify which book is being referred to. Without this clause, the sentence would be incomplete and ambiguous.

A non-restrictive clause, also known as a non-essential or non-defining clause, provides additional information about the noun or pronoun it modifies but is not necessary for the sentence's core meaning. Non-restrictive clauses are set off by commas and can be removed from the sentence without altering its essential meaning or grammatical structure.

For example:
- My sister, who is a doctor, lives in New York.
In this sentence, the non-restrictive clause "who is a doctor" provides additional information about the noun "my sister." However, if we remove this clause, the sentence would still convey the same essential meaning: "My sister lives in New York."

It is important to note that non-restrictive clauses often contain relative pronouns such as "who," "which," or "that." These pronouns introduce the clause and refer back to the noun or pronoun being modified.

In summary, the key difference between restrictive and non-restrictive clauses lies in their necessity for the sentence's meaning. Restrictive clauses are essential and cannot be removed without altering the sentence's core meaning, while non-restrictive clauses provide additional information but can be omitted without affecting the sentence's essential meaning.