Subject-verb agreement, also known as subject-verb concord, is a grammatical rule that requires the verb or verbs in a sentence to match the number, person, and gender of the subject. In English, the verb needs to match just the number and sometimes the person of the subject. The basic rule of subject-verb agreement is that a singular subject takes a singular verb, while a plural subject takes a plural verb. For example, "The dog barks" is correct, while "The dog bark" is incorrect. However, there are some exceptions to this rule, such as when the subject is composed of two or more nouns or pronouns connected by "and," in which case a plural verb should be used. Similarly, when a compound subject contains both a singular and a plural noun or pronoun joined by "or" or "nor," the verb should agree with the part of the subject that is closest to the verb.

Subject-verb agreement can be difficult to master, but it is an important aspect of writing and speaking correctly in English. Mistakes involving subject-verb agreement are noticeable to native speakers and may be perceived as a lack of language skills in a professional setting. To avoid errors, it is important to identify the subject and verb of a sentence and ensure that they agree in number. Practicing identifying the subject and verb of a sentence can help improve subject-verb agreement skills.