This document discusses different verb tenses including:
1. Simple past and present tenses - past tense verbs describe actions that have already happened while present tense verbs describe actions happening now.
2. Irregular verbs - some verbs have irregular past tense forms that do not follow the standard adding "-ed" rule.
3. Progressive tenses - these tenses indicate whether an action was ongoing in the past (past progressive) or is ongoing now (present progressive).
4. Present perfect tense - this tense indicates an action started in the past and may still be relevant now, using "have/has" plus the past participle verb form.