Copular verbs, also known as linking verbs, connect the subject of a sentence to a subject complement, which can be a noun, pronoun, or adjective. The most common copular verb is to be, but others include seem, become, and appear. These verbs do not express action; instead, they describe a state of being or condition. In a sentence like "The sky is blue," the verb "is" links the subject "the sky" to the adjective "blue," which describes its state. Copular verbs help convey information about identity, qualities, or states, making them essential for clear communication in English.