Conditionals. Clasification.

 Conditionals are clasified in real and unreal. 

Real conditionals are those in which, if the depedendant clause happens, the main clause is certain or almost certain. This conditionals are subdivided in the zero conditional and the first conditional. The dependant clause usually is in present (even though it has a future meaning) but could be in present continuous too.

Unreal conditionals are refered to false,impossible or past situations. They comprehend the second and third conditionals. Unreal presents a curious grammar exception: When the dependant clause includes the verb be, were is used for all the subjetcs (despite of this, in spoken english is common to hear was).

 For a deeper understanding, there it is a video from the Oxford Online English website.