Strategy and Tactics
Chess strategy consists of setting and achieving long-term goals during the game — for example, where to place different pieces — while tactics concentrate on immediate maneuver. These two parts of chess thinking cannot be completely separated, because strategic goals are mostly achieved by the means of tactics, while the tactical opportunities are based on the previous strategy of play.
Because of different strategic and tactical patterns, a game of chess is usually divided into three distinct phases: Opening, usually the first 10 to 25 moves, when players develop their armies and set up the stage for the coming battle; middlegame, the developed phase of the game; and endgame, when most of the pieces are gone and kings start to take an active part in the struggle.
The most basic way to evaluate one's position is to count the total value of pieces on both sides. The point values used for this purpose are based on experience. Usually pawns are considered to be worth one point, knights and bishops three points each, rooks five points, and queens nine points. The fighting value of the king in the endgame is approximately four points. These basic values are modified by other factors such as the position of the piece (e.g. advanced pawns are usually more valuable than those on their starting squares), coordination between pieces (e.g. a bishop pair usually coordinates better than the a bishop plus a knight), and the type of position (knights are generally better in closed positions with many pawns, while bishops are more powerful in open positions).
Values of the pieces
Bishops and knights are called minor pieces. A knight is about as valuable as a bishop, but less valuable than a rook. Rooks and the queen are called major pieces. Bishops are usually considered slightly better than knights in open positions, such as toward the end of the game when many of the pieces have been captured, whereas knights have an advantage in closed positions. Having two bishops is a particularly powerful weapon, especially if the opposing player lacks one or both of his bishops.
Three pawns are more likely to be useful than a knight in the endgame, but in the middlegame a knight is often more powerful. Two minor pieces are stronger than a single rook, and two rooks are slightly stronger than a queen.
One commonly used simple scoring system is:
Piece Value
Pawn 1
Bishop 3
Knight 3
Rook 5
Queen 9
** Under a system like this, giving up a knight or bishop in order to win a rook ("winning the exchange") is advantageous and is worth about two pawns. This of course ignores such complications as the current position and freedom of the pieces involved, but it is a good starting point. In an open position, bishops will be more valuable than knights (a bishop pair can easily be worth seven points or more in some situations); conversely, in a closed position, bishops will be less valuable than knights. The king is infinitely valuable since its loss causes the loss of the game. **
Space
All other things being equal, the side which controls more space on the board has an advantage. More space means more options, which can be exploited both tactically and strategically. If all of one's pieces are developed and no tactical tricks or promising long-term plan is apparent, he could try to find a move which will enlarge his influence, particularly in the center. However, in some openings, one player will accept less space for a period of time to set up a counterattack in the middlegame. This is one of the concepts behind hypermodern play.
## Hypermodernism is a school of chess thought which advocates controlling the centre of the board with distant pieces rather than with pawns, thus inviting the opponent to occupy the centre with pawns which can then become objects of attack. ##
Defending Pieces
It is important to defend one's pieces even if they are not directly threatened. This helps stop possible future campaigns from the opponent. This approach has an antecedent in the theory of Aron Nimzowitsch who referred to it as "overprotection." Similarly, if one spots undefended enemy pieces, one should take advantage of those pieces' weakness.
Exchanging pieces
To exchange pieces means to capture a hostile piece and then allow a piece of the same value to be captured. As a general rule of thumb, exchanging pieces eases the task of the defender who typically has less room to operate in.
Exchanging pieces is usually desirable to a player with an existing advantage in material, since it brings the endgame closer and thereby leaves the opponent with less time in which to recover ground. In the endgame even a single pawn advantage may decide the game.
When playing against stronger players, many beginners attempt to constantly exchange pieces "to simplify matters". However, stronger players are often relatively stronger in the endgame, whereas errors are more common during the more complicated middlegame.
Note that "the exchange" may also specifically mean a rook for a bishop or knight.Specific pieces
Pawns :: In the endgame, passed pawns, those which cannot be hindered by enemy pawns from promotion, are strong, especially if they are advanced or protected by another pawn. A passed pawn on the sixth row is roughly as strong as a knight or bishop and will often decide the game. (Also see isolated pawn, doubled pawns, backward pawn, connected pawns).
## In chess, a passed pawn is a pawn with no opposing pawns to prevent it from advancing to the eighth rank, i.e. there are no opposing pawns in front of it on the same file (Column) nor on an adjacent file. A passed pawn is sometimes colloquially called a passer. Passed pawns can be an advantage because only the opponent's pieces can prevent them from promoting.
## In chess, an isolated pawn is a pawn for which there is no friendly pawn on an adjacent file. An isolated queen's pawn is often called an isolani.
## In chess, doubled pawns are two pawns of the same color residing on the same file. Pawns can become doubled only when one pawn captures onto a file on which another friendly pawn resides.
## In chess, a backward pawn is a pawn that is behind the pawns of the same color on the adjacent files and that cannot be advanced without loss of material, usually the backward pawn itself.
## In chess, connected pawns are two or more pawns of the same color on adjacent files, as distinct from isolated pawns. These pawns are instrumental in creating pawn structure because, when diagonally adjacent, like the two rightmost white pawns, they form a pawn chain, a chain where the one behind protects the one in front.
Knights :: Since knights can easily be chased away with pawn moves, it is often advantageous for knights to be placed in "holes" in the enemy position (an outpost), squares where they cannot be attacked by a pawn. Such a knight on the fifth rank is a strong asset, and one on the sixth rank may exercise as much power as a rook. A knight at the edge or corner of the board controls fewer squares than one on the board's interior.
Bishops :: A bishop always stays on squares of the color it started on, so once one of them is gone, the squares of the other color become more difficult to control. When this happens, pawns moved to squares of the other color do not block the bishop, and enemy pawns directly facing them are stuck on the vulnerable color.
Rooks :: Rooks have more scope of movement on Half-open files (ones which do not contain pawns of one's own colour). Rooks on the seventh rank can be very powerful as they attack pawns which can only be defended by other pieces, and they can restrict the enemy king to its back rank. A pair of rooks on the player's seventh rank is often a sign of a winning position.
In middlegames and endgames with a passed pawn, Tarrasch's rule states that rooks, both friend and foe of the pawn, are usually strongest behind the pawn rather than in front of it.
## A File is a column of the chessboard. A specific file can be named either using its position in algebraic notation, a–h, or by using its position in descriptive notation. For example, the f-file or the king bishop file comprises the squares f1–f8 or KB1–KB8.
## In chess, a Half-open file, or semi-open file, is a file with no pawns of one color. In the diagram, the e-file is a half-open file for White, and the d-file is a half-open file for Black. A half-open file can provide a line of attack for a rook or queen.
## The Tarrasch rule is a general principle that applies in the majority of chess middlegames and endgames. Siegbert Tarrasch stated the "rule" that rooks should be placed behind passed pawns – either yours or your opponent's. This "rule" is usually true, but not always. Tarrasch has been quoted as saying, "Always put the rook behind the pawn.... Except when it is incorrect to do so."
Queen :: Queens are the most powerful pieces. They have great mobility and can make many threats at once. For these reasons, mating attacks involving the queen are easier to achieve than those without. It is generally wise to wait to develop the queen until after the knights and bishops have been developed to prevent the queen from being attacked by minor pieces and losing tempos.
King :: During the middle game, the king is often best protected in a corner behind his pawns. If the rooks and queen leave the first rank however, an enemy rook can checkmate the king by invading the first rank. Moving one of the pawns in front of the king (making a luft) can allow it an escape square, but may weaken the king's position.
The king can become a strong piece in the endgame. With reduced material, a quick mate is not an immediate concern anymore, and moving the king towards the center of the board gives it more opportunities to make threats and actively influence play.
Chess Tactics
In chess, a tactic refers to a short sequence of moves which limits the opponent's options and results in tangible gain. Tactics are usually contrasted to strategy, in which advantages take longer to be realized, and the opponent is less constrained in responding.
The fundamental building blocks of tactics are two-move sequences in which the first move poses a double threat. The opponent is unable to respond to both threats in one move, so the first player realizes an advantage on the second move. This includes forks, skewers, discovered attacks, x-ray attacks, undermining, overloading, and interference. Pins also fall into this category to some extent, although it is common for a defending player to relieve neither of the two threats posed by a pin, in which case the attacking player commonly maintains the pin for a longer period of time. A pin is therefore sometimes more strategic than tactical.