19. English - Mastering Comamas in Defining and Non-Defining Relative Clauses

Mastering commas in relative clauses is essential for clear writing. The core error involves misusing commas with defining and non-defining clauses. Defining clauses provide essential information to identify the noun; therefore, they never take commas. For example, *"The car that I bought is red"* needs no punctuation. Conversely, non-defining clauses offer extra, non-essential details and must be enclosed in commas, as in *"My car, which is red, is fast."* Writers frequently make the mistake of isolating essential defining clauses with commas or omitting them around non-defining clauses, completely altering the sentence's meaning and logical flow.