Zero Conditional - (Type Zero) - Situación siempre verdadera
If you freeze water, it turns into ice.
First Conditional - (Type I) - Situación real o posible
If it rains today, I'll stay at home.
Second Conditional - (Type II) - Situación hipotética
If I won the lottery, I would travel around the world.
Third Conditional - (Type III) - Situación hipotética del pasado
If I had won the lottery, I would have traveled around the world.