Knight (chess) king); in descriptive chess notation, "Kt" is sometimes used instead, mainly in older literature. In chess problems and endgame studies, the letter "S", standing for the German name for the piece, "Springer", is often used (and in some variants of fairy chess "N" is used for the popular fairy chess piece, the nightrider). Even among sets of the standard Staunton pattern, the style of the pieces varies. The knights vary considerably. Here are some examples. The knight, along with the king and the rook, has the oldest defined movement of any chess piece, its movement being unchanged since the invention
Fairy chess piece "pao" and "vao" (derived from the Chinese cannon) and the "mao" (derived from the horse). Those derived from the cannon are distinguished by moving as a hopper when capturing, but otherwise moving as a rider. Pieces from xiangqi are usually circular disks, labeled or engraved with a Chinese character identifying the piece. Pieces from shogi (Japanese chess) are usually wedge-shaped chips, with kanji characters identifying the piece. Fairy pieces vary in the way they move, but some may also have other special characteristics or powers. The joker (in one of its definitions) mimics the last move made by the opponent.