Is En Passant Real?

First off what are the rumors of en passant? Well they say that if a pawn advances twice (on its first move) to pass over the square another pawn can take then the enemy pawn can take it:

Well i come to tell you that it is real! And its exactly what people say. But, you can only do it on the next turn that the pawn advanced:

But is this move useful? well look at this position:

  What should white play next? They cannot stop this new passed pawn that black has! They should play dxe6. Now white is completely wining the game! so now black is in trouble.

Did you see? But this move is not too common, lets look at a position:

White is down too much material and wants to badly push the a-pawn to promote and it only has one enemy stopping it. The pawn on b4. What if white sacrifices the bishop for the pawn? attacking the queen and freeing the pawn?

See? Now the pawn if free! Now its important to note that en passant cannot be done like this:

The pawns must be side by side:

now here is a puzzle:

For more on en passant please check out chess.coms official page on the topic:  https://www.chess.com/terms/en-passant