Definition: Relative non-defining clauses provide additional information about a noun or pronoun but do not limit or define it. They are introduced by relative pronouns.

Function: They add extra context without changing the main meaning of the sentence.

Example: "The teacher, who has taught for 20 years, is retiring."

Example: "The author, whom I admire, will be giving a lecture."

Example: "The car, whose owner is my neighbor, is parked outside."

Example: "The novel, which was published last year, became a bestseller."