This document discusses the different perfect tenses in English including the present perfect, present perfect continuous, past perfect, past perfect continuous, future perfect, and future perfect continuous. It provides the forms and uses for each tense. The present perfect is used to refer to an unspecified time before now or to show duration from the past until now. The present perfect continuous emphasizes duration or recentness. The past perfect refers to events completed before something in the past. The future perfect refers to events completed before something in the future.