The document discusses the different types of conditionals in English grammar. There are four main types: zero conditional, first conditional, second conditional, and third conditional. Each type has a specific usage and structure. The zero conditional refers to general truths and uses the simple present tense. The first conditional refers to possible present or future situations and uses the present simple and future simple. The second conditional refers to hypothetical or unlikely situations and uses the past simple and present conditional. The third conditional refers to unlikely past situations and uses the past perfect and perfect conditional. Examples are provided to illustrate each type of conditional.