The document discusses the present perfect tense and its uses. The present perfect tense is used to discuss experiences or events that started in the past and are still ongoing or relevant to the present. It can refer to an indefinite past action where the time is unknown, or repeated past actions over a period of time. The present perfect tense uses the auxiliary verbs have or has combined with the past participle of the main verb. It also discusses how adverbs like already, never, ever, before and since/for can be used with the present perfect tense.