This document discusses the four conditional tenses in English. It explains that conditionals show actions that happen, will happen, or might have happened depending on certain conditions. The four types of conditionals are then defined: zero conditional uses present tense, first conditional uses present and future, second conditional uses past and conditional mood, and third conditional uses past perfect and conditional perfect. Examples are provided for each conditional along with their typical structures and uses for expressing possibilities, wishes, or regrets depending on present or past conditions.