0Conditionals / The If Clause:
A conditional sentence shows that an action is reliant on something else (there's a condition).
The two most common conditionals are real and unreal, they are sometimes called if-clauses.
The real conditional (often named 1st Conditional) describes situations based on fact.
The unreal conditional (often named 2nd Conditional) describes unreal or imaginary situations.
There is also what we call the 3rd conditional, used to express no possibility of something having happened in the past, and the zero conditional is used to express absolute certainty.
Unless you are studying English to pass an exam or test don't try to remember the types, just learn the structure so that you know how to express the meaning conveyed by each type, it's going to happen, it's only going to happen if something else happens, it's never going to happen.
Note: You can swap if clauses around, but if the "if" clause comes first, a comma is usually used, but if the "if" clause comes second, there is no need for a comma.
