An open file is a file that has no pawns on it.  Either player can place a rook on an open file to control all of the squares on that file. 

A half-open file is a file that has pawns of only one color on it.  A player can place a rook on a half-open file to control all of the open squares on that file and attack the opponent’s pawn. 

It is very important to understand different types of tactics in order to fully realize your chess potential. Previously we published articles on this topic, feel free to review Direct Tactics and Dynamic Tactics ideas before you jump into discovered tactics section.

Discovered tactics occur when you move a piece out of the way to uncover another piece.  The piece in front blocks the piece behind it, and you move the piece in front out of the way.

An outpost square is a square that cannot be attacked by the opponent’s pawns.  If you occupy an outpost square with one of your pieces, it is difficult for the opponent to force your piece off that square. 

Since he cannot use a pawn to eject your piece, he must use another piece.  Sometimes, there is no piece available to eject you from an outpost square.  This makes an outpost square very powerful, especially if it is in the center of the board, or deep in the opponent’s territory, or near the opponent’s king.