A clause is a group of words that contains a subject and a verb. Every sentence you write or speak contains at least one clause, and often more. In “The dog barked,” that's a complete clause with a subject (the dog) and a verb (barked). In “When the bell rang, everyone rushed outside,” you have two clauses: “when the bell rang” and “everyone rushed outside.”

Some clauses can stand alone as complete sentences. These are called independent clauses because they express a complete thought. Other clauses depend on additional information to make sense. In “because I studied hard,” you have a subject (I) and a verb (studied), but it leaves you hanging. Because you studied hard, what happened? You need to add an independent clause: “I did well on the test because I studied hard.”

Understanding clauses helps you write more interesting sentences. Instead of writing short, choppy sentences like “The storm came. We went inside. We were safe,” you can combine clauses: “When the storm came, we went inside, and we were safe.”

The word clause also appears in legal and formal contexts, meaning a specific section or provision in a document. A contract might have a clause about payment terms, or a treaty might include a clause about resolving disputes.