The King can move in any of the 8 directions (up, down, left, right, and 4 diagonals), but only 1 square at a time. The King moves slowly. It can only move to the squares immediately adjacent to the Kings square. The King is allowed to move forwards or backwards, anywhere on the board, provided that it doesnt stray into check.
There is one special move called Castling where the King moves 2 squares towards its own Rook, then the Rook is jumped over to the other side of the King. The squares between the King and its Rook must be empty, so no jumping is possible. There are also a number of other special Castling Rules such as that you are not allowed to Castle Out of Check.
King Capture Moves
Kings are allowed to capture enemy pieces. They can attack a piece and may capture it. However, Kings are limited in that they are never legally allowed to be under attack. So a King cannot take an enemy piece if that piece is actually protected by a second enemy piece or pawn. If it did, then the second enemy piece would take the King (game over). But a King can take an unprotected piece and it is a common beginner mistake to put a Queen up on the King and announce checkmate, when in fact the King can simply take the Queen.
Checks against the King are a special situation in chess. In the usual rules, you cannot leave your King in check, or move the King into check, or move a pinned piece thereby creating check. If the King is left in check, this is an illegal move and must be undone. Only in some different tournament rules, such as in Lightning Chess, is it allowed to take the King (which wins in these tournaments) rather than re-play the illegal move. In slower tournaments, the players must undo the illegal move, and play something else.
Two Kings Cannot Meet
One particular limitation is that two Kings can never approach each other. They can only get as close as having one empty square between them (called The Opposition). A King cannot attack the other King, nor can it capture the other King, except in rare situations in rapid-play tournaments where illegal moves and take the King is an allowed way to win.
Related Chess Rules Topics
Read more about these related chess rules, chess puzzles, and other chess tactics and strategies: