Action by a long-range piece (queen, rook or bishop) immobilizing an ennemi piece which, if moving, will expose one of its friendly piece having a greater value. The pin is considered " absolute " when the exposed piece is the King since the pinned piece is forbidden from moving to avoid a check (thus preventing an illegal move).
Pattern usually done in the opening developing a bishop on the flank by advancing a knigh-pawn (b or g pawn) by one square.
We say that the bishop is in fianchetto when it occupies the square freed by the pawn. Once occupying the square, the bishop
can participate in the control for the center from a distance and has an influence on one of the big diagonal (h1-a8 or a1-h8).
In the diagram below, the g7 bishop is in fianchetto.
Définition according to Wikipedia:
In chess, the fortress is an endgame drawing technique in which the side behind in material sets up a zone of protection around their king that cannot be penetrated by the opponent. More details on Wikipedia.
Situation when a piece is threatening several pieces by the same time and where the defender cannot save them all.
Chess engine developed by Chessbase used for playing and analysing chess games with a computer. This chess engin can play at the grand-master level and is a great training tool for the amateur. Other chess engines are available: Shredder, Rybka, The King, etc.
A gambit is a move offering a pawn to the opponent in exchange of active play in the opening.
A special move involving the king and one of its rook usually done in the opening to activate the rook and secure the king. For more details about this special move, consult lesson 5 on Advanced And Special Rules.
A tempo is a time unit corresponding to a player's turn to play. When a player succeeds in winning a tempo, it means that is opponent was forced to play a defensive move against an important threat. A player is usually able to win a tempo when developing a piece on a useful square by attacking one of the opponent's pieces having a greater value. Winning tempi (plural form) gives an advantage because it allows to grasp more squares and gives an edge over the opponent in the development of pieces.
Chess theory refers to the study of opening variations from high level games. Several high-level players judge the effectiveness of an opening variation by analysing statistcs about the number of wins/losts and draws coming from this variation. Chess theory helps in saving time during a preparation by classifying openings according to their first moves and efficiency.
Zeitnot occurs when a player needs to play several moves in a very short period of time in order to reach the time control defined for the game. For example, if the time control for the game gives each player 90 minutes to play their first 40 moves and an extra 60 minutes to finish the game, a player would be in time pressure if he takes, let say, 75 minutes to play its first 20 moves. Only 15 minutes will remain to play 20 moves for this player. While in Zeitnot, a player usually feels the time pressure and does not have enough time to do a deep analysis of the position, causing mistakes or big blunders that might give the victory to his opponent.
Term borrowed from German language defining a situation where one player is put at a disadvantage because he has to make a move when he would prefer to pass and make no move. To be in Zugzwang means that any move available to a player is a loosing move but since the player cannot pass its turn, he is forced to play a move that severly hurts his position.