This document discusses English verb tenses. There are three main tenses - present, past, and future. Each tense has four forms: indefinite, continuous, perfect, and perfect continuous. The tenses are used to indicate whether an action is ongoing, completed, or will occur in the future. For example, the present continuous tense indicates an action that is happening now, the past perfect tense refers to an action that was completed before another past action, and the future perfect continuous tense refers to an action that will be ongoing up to a point in the future.