The document discusses the different types of conditionals in English:
1) Zero conditional - uses present tense to talk about situations that are always true.
2) First conditional - uses present tense and future tense to talk about possible or probable situations.
3) Second conditional - uses past tense and conditional tense to talk about hypothetical situations.
4) Third conditional - uses past perfect tense and conditional perfect tense to talk about hypothetical situations in the past. Examples are provided for each type of conditional.