Material is one of the most important concepts in chess. Fortunately, it's also very easy to understand. When we talk about material, we mean all the pieces a particular player has on the board. Normally when talking about material, we also mean the value of the pieces. If one player has a greater value of pieces on the board than the other, then that player is said to have a material advantage. Likewise, the player with a lesser value of pieces on the board is at a material disadvantage.
How do we know whose pieces are more valuable? Although pieces may be more or less valuable depending on their position on the board (for example, a pawn that is one move away from becoming a queen is certainly more valuable than a pawn still on its starting square), the material value of the piece never changes - after all, a piece can be moved to a better or worse square, but a pawn is still a pawn and a queen is still a queen. Each type of piece is considered to have a specific numeric value, given below:
These traditional piece values were worked out many years ago, and players today generally agree that they are correct. For example, years of practical play have more or less proven that a queen is generally more valuable than a rook and bishop, but less valuable than two rooks. Although bishops and knights traditionally have the same value, many players prefer bishops and sometimes you will see them given a half point advantage over a knight. While this is a matter of taste, it is generally true that having both bishops is slightly better than having a bishop and knight or two knights. If one player has two bishops and the other player does not, then that player is said to have the Bishop Pair, and all other things being equal, is considered to have a slight material advantage.
You don't get points for capturing pieces, as there is no scoring in chess, so why bother giving values to the pieces? The values of the pieces are more important in determining who has the greatest amount of firepower on the board at any given moment. In general, it is almost always good to have a material advantage, because it means you have a bigger and more powerful army than your opponent. Even a single pawn can be enough of a material advantage to win the game - after all, it can become a queen later.
Here are some positions to test your knowledge of the material values of the pieces. On the board below, find the move that gives white a material advantage of four points.
On the board below, black is at a material disadvantage. Find a move that will give black a material advantage.
On the final board material is equal, but black is threatening to capture white's rook. Find a move that will avoid this and gain a material advantage of three points for white instead.