The subject is the person, animal, thing, or concept that the sentence is about. The verb is the action or state of being of the subject. Using the subject and verb correctly is important for clear communication. In English, the subject usually comes before the verb in a sentence. For example, in the sentence "She sings," "She" is the subject and "sings" is the verb. It's important to match the subject and verb in terms of number and person (singular/plural and first/second/third person) for the sentence to make sense. For example, "He sings" uses a singular subject with a singular verb, while "They sing" uses a plural subject with a plural verb.