The document discusses the differences between using the present perfect and simple past tenses in English. It provides examples of when to use each: - The present perfect is used for actions that began in the past and continue in the present, or when the result of the action is relevant now. The simple past is used for actions fully in the past. - Signal words like "already" or "for" indicate unfinished time requiring present perfect, while words like "yesterday" or specific past times use simple past. - Examples show using the present perfect to discuss current relevance or unfinished timelines, and simple past for finished past actions or times.