Auxiliaries, also known as auxiliary verbs, are helping verbs that accompany main verbs to add meaning or clarify tense, mood, or voice. Common examples include be, have, and do. They help form questions, negatives, and various verb tenses, such as the present perfect ("I have eaten") or the passive voice ("The book was written"). In English, auxiliaries can also include modal verbs like can, will, and should, which express ability, possibility, or necessity. By using auxiliaries, speakers can convey more complex ideas and nuances in their sentences, making communication clearer and more effective.