It consists of a main clause and one or more subordinate clauses. The subordinate clause is either a noun clause, an adjective clause or an adverb clause.
The noun being modified acts as the subject of an adjective clause.
Relative pronouns introduce adjective clauses.
Punctuation: Commas are used in non-defining adjective clauses.
Punctuation: No commas are used in defining adjective clauses.
