This document discusses and classifies verb tenses. It describes how tenses can be categorized based on time frame into present, past and future tenses. Tenses can also be categorized based on aspect into simple, continuous, perfect and perfect continuous forms. The document provides definitions and examples of 12 tenses - present indefinite, present continuous, present perfect, present perfect continuous, past indefinite, past continuous, past perfect, past perfect continuous, future indefinite, future continuous, future perfect and future perfect continuous. Rules and examples of using each tense are listed.