Pawn value is only one so is okay to lose tree pawns for one enemy knight. Remember that this is only clear statistic not always is good to spear 3 pieces for one Knight or Bishop. You should remember that good pawn's game is key to victory! In the last part of game – ending single pawn can change defeat in to Victory! So always try to save as many pawns as you only can.
Pawn can go only straight and only forward! Range of pawns is low one field in one move.
Pawn can't go back!
Pawns are like Infantry when they are fresh they can go more than one field. When you use first time this pawn in the game, you can decide between: move only one field or two fields in one move. Remember that pawn can make this only when you use this pawn first time. For example if you at first use your pawn on a2 and go one field straight to a3 in next move you can go only one field forward so on the a4 because this is second move of this pawn. But if this is first move, and you decide to go 2 fields you can go from a2 to a4 in one move.
