The document discusses auxiliary verbs and how they are used to form verb phrases and tenses in English. It defines auxiliary verbs as "helping" verbs that are used along with a main verb to convey meanings like time, aspect, modality, voice, and emphasis. The key auxiliary verbs are be, do, have, and the modal auxiliaries (can, could, may, etc.). Examples are provided to illustrate how auxiliary verbs are used to form the present, past, future, progressive, perfect, and emphatic tenses, as well as passive voice. The roles and functions of specific auxiliary verbs like be, do, have, and the modal auxiliaries are explained in detail.