The essence of this improvement lies in next features:
The properties of the pawns, their position in the game and their positive and negative side are well known. Since the foundation of European chess 500 years ago chess was played without the understanding of the position principles. The pawns were only attackers and cheap casualties. Although today we understand the pawns differently, the impression that the pawn is a weak figure remains.
When making a capture a pawn moves one field diagonally. When moving back the pawn can't make a capture by moving diagonally backwards, but it can attack by the rules of moving forward.
On reaching the last rank the pawns can be exchanged for another piece (a Queen, a Rook, a Bishop, or a Knight), but it can only be replaced by the piece, which was previously captured by the opponent.Promotion also takes place if on its final move the promoted pawn made a capture. Exchange for the King is not allowed.
Promotion is not obligatory, the pawn can keep his function as a pawn and stay in the game.