In chess, development refers to the movement of pieces in the initial stages of the game. When a piece moves for the first time, it is said to have been 'developed', and in most chess openings, the idea is to develop all one's pieces before forming a plan for the rest of the game. The first player, therefore, to complete the development of his pieces has an advantage because he can start active operations sooner. The rules of development, or rather guidelines, since in chess there are numerous exceptions to almost every rule, are as follows:
- Don't make too many pawn moves. This wastes time and may allow your opponent to complete development before you. Generally two or three pawn moves are sufficient to allow all pieces to be developed.
- Don't move a piece twice. This also wastes time. Move your pieces to their best squares first time.
- Try to develop knights before bishops. The best square for a knight is usually obvious earlier than the best square for a bishop.
- Castle early. This is very important in open games (for example, double king pawn or e4 e5 openings). It is less important in closed openings, for example certain variations of the King's Indian Defence, but it is still wise to castle before forming a plan, unless you have a good reason to delay it. A king exposed in the center of the board can lead to all kinds of problems.
- Control the center. Knights, for example, are far more powerful in the middle of the board than at the edge, which is why, for White, the move Nf3 (or Nc3) in the first few moves is almost always better than Nh3 (or Na3). There's no advantage to developing quickly if your opponent controls the center completely, as the center is the base for most attacking and defensive plans.
- Don't move your queen out too early. Moving the queen out in the first few moves can often lead to it being attacked by the opponent's pieces, and because the queen is the most valuable piece, it almost always has to move when being attacked. This allows the other player to gain time. Only develop the queen the minor pieces have already moved, and (usually) only develop it one square forward (to c2, d2 or e2, or for Black, c7, d7 or e7).
- Make development difficult for your opponent. If he violates one of the above rules, see if you can exploit it, for instance by attacking an exposed queen. If he has left a weak square in the center, develop your pieces so that they focus on the weakness.
- Development is finished, as a rule of thumb, when the rooks are connected along the back rank. In other words, if the minor pieces are developed and the king is castled, then once the queen moves forward, development is finished and you can start trying to formulate a plan.
Development is so important in chess that many players will sacrifice a pawn or even more in order to develop quickly. This is called a gambit, and a player who accepts gambited material needs to be very careful - an advantage of only two or three moves of development can lead to a very quick attack. Gambits were extremely popular in the first decades of the modern chess era, producing many brilliant and short games, before defensive play became an art in itself. Nowadays, a grandmaster has to be adept at both attack and defense, and gambits are much rarer, though some gambits, because of their strength, and the lead in development that they confer, will never become extinct (see Benko Gambit for an example).
The above guidelines can be and regularly are violated by individual chess openings - this does not mean that they are wrong, merely that there is room in chess for experimentation and innovation. There have been long periods in the world history of chess where one particular style of play was more fashionable or more highly regarded than another - see hypermodern chess. Today's top grandmasters, such as Garry Kasparov and Vladimir Kramnik play with a style that includes the lessons learned from all previous eras and masters