The document discusses tense and aspect in language. Tense locates events in time as past, present, or future relative to the time of utterance. Aspect describes how events unfold over time, such as whether they are ongoing (progressive) or completed (perfect). The simple, progressive, and perfect aspects are explained along with how they are marked grammatically and how they convey different meanings about an event's timing or completion. Examples are provided to illustrate the different tenses and aspects.