The document defines conjugating a verb as changing its form from the infinitive (e.g. to eat) to agree with the subject and tense, such as "I eat" or "they slept". There are six subjects in English (I, you, he/she/it, we, you plural, they) that determine the verb form. If asked to conjugate a verb, one lists all its forms for a given tense, such as the six forms of "to be" in the present tense (I am, you are, etc.). Regular verbs follow patterns, while irregular verbs must be memorized due to not following patterns.