This document summarizes the different types of conditional clauses in English. Conditional Type 0 uses the present tense and is used to express factual conditions. Conditional Type 1 uses "if" with the present tense and "will" future to express likely conditions. Conditional Type 2 uses "if" with the past tense and "would" to express unlikely conditions. Conditional Type 3 uses "if" with the past perfect and "would have" to express impossible past conditions. Examples are provided to illustrate the different conditional types and their structures.

1. Conditional Clauses