The document explains the present perfect tense, including its structure and usage. The present perfect tense is used to talk about an action that began in the past but continues into the present. It is formed using the present tense of the verb "have" and the past participle of the main verb. The present perfect tense is used to express experiences, the number of times an action has occurred, and situations that started in the past but are still ongoing. It can include words like "since" to indicate a starting point and "for" to indicate duration.