An SAT micro-topic explainer. Free to read — no account needed.
An independent clause is a complete thought: it contains a subject and a verb and could end with a period on its own. Recognizing one is a matter of finding those two parts and checking that together they form a full sentence.
Locate who or what the clause is about (the subject) and the action or state (the verb). If together they make a complete thought that could stand as its own sentence, the clause is independent.
Strip out any non-essential phrase first, since it can hide the core. "The Apollo 11 mission, which landed humans on the Moon, was a triumph" reduces to "The Apollo 11 mission was a triumph" — clearly independent, with subject "mission" and verb "was."
Contrast this with a dependent clause, which opens with a subordinating conjunction (because, as, when, although) and cannot stand alone even though it has a subject and verb. "Because the movies were popular" is not independent.
Worked examples
Is "silent movies were a popular form of entertainment" independent? Yes. The subject is "silent movies," the verb is "were," and it stands alone as a complete sentence.
Is "Prior to this innovation, books were copied by hand, limiting their availability" independent? Yes. Remove the extra phrase "limiting their availability"; "books were copied by hand" stands alone, with subject "books" and verb "were copied."
Is "because they blend action and comedy seamlessly" independent? No. It has a subject and verb but begins with the subordinating conjunction "because," so it cannot stand alone — it is dependent.
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