This document describes the four types of conditional sentences in English: 1) Type 0 or "Zero Conditional" uses the simple present tense and describes general truths or laws. 2) Type 1 or "First Conditional" uses the present tense in the if-clause and will or may in the main clause to talk about probable future events. 3) Type 2 or "Second Conditional" uses the past tense in both clauses to talk about hypothetical or imaginary situations in the present or future. 4) Type 3 or "Third Conditional" uses the past perfect tense in both clauses to talk about imaginary situations in the past.