The document discusses the past simple tense in English. It is used to talk about actions that took place in the past and have already ended. There are two types of verbs in the past simple tense: regular verbs which add "-ed" and irregular verbs which have varying conjugations. The past simple tense can be used affirmatively with the structure "subject + verb + complement", interrogatively by placing "did" before the subject, and negatively with "did not" placed before the verb.