This document provides an overview of the differences between present simple and present continuous tenses, and between past simple and past continuous tenses in English grammar. It outlines the affirmative, negative, and interrogative forms of each tense and provides examples of when each tense is typically used, such as using present simple for routines/habits and present continuous for ongoing actions. It also notes that past simple is used for completed past actions while past continuous is used for ongoing actions at a specific time in the past.