1. ZERO CONDITIONAL
1.1. talk about things that are always true like scientific facts, general habits.
1.1.1. IF + PRESENT SILMPLE > PRESENT SIMPLE
1.1.1.1. if you add two and two you get four
1.1.1.1.1. IN THE RESULT I CAN USE IMPERATIVES / CAN
1.1.1.1.2. THE SITUATION CAN BE INTRODUCED BY unless
2. FIRST CONDITIONAL
2.1. Possible or likely things in the near present or in the future
2.1.1. IF + PRESENT SIMPLE > FUTURE WITH WILL
2.1.1.1. if it rains later, we'll stay at home
2.1.1.1.1. IN THE RESULT I CAN USE MAY / MIGHT
2.1.1.1.2. THE SITUATION CAN BE INSTRODUCED BY unless / when
3. SECOND CONDITIONAL
3.1. Impossible things in the present / unlikely things in the future
3.1.1. IF + PAST SIMPLE > WOULD + BASE FORM
3.1.1.1. if I won the lottery I would sail round the world
3.1.1.1.1. THE SITUATION CAN BE INTRODUCED BY could / might
4. THIRD CONDITIONAL
4.1. Things that didn't happen in the past with their imaginary results
4.1.1. IF + PAST PERFECT > WOULD + HAVE + PAST PARTICIPLE
4.1.1.1. if had studied harder I would have passed the exam
4.1.1.1.1. THE SITUATION CAN BE INTRODUCED BY could have / might have
5. MIXED CONDITIONAL
5.1. Present result of a past situation which didn't happen
5.1.1. IF + PAST PERFECT > WOULD + BASE FORM
5.1.1.1. if I had listened to your advice, I wouldn't be in such a mess
5.1.1.1.1. THE SITUATION CAN BE INTRODUCED BY could / might