There are four types of conditionals in English: 1) The Zero Conditional uses the simple present tense and describes situations where an action always leads to a certain result. 2) The First Conditional uses the simple present and future tenses to talk about possible situations in the future. 3) The Second Conditional uses the past tense and "would" to talk about unlikely or imaginary future situations. 4) The Third Conditional uses the past perfect tense and "would have" to talk about unlikely past situations and their possible results.