A Rubik's Cube is a puzzle game invented by a Hungarian architecture professor named Erno Rubik. The puzzle is three-dimensional, with 26 different cubes all attached to each other, each one of six different colors (red, white, blue, green, yellow, orange). They interlock to form one big, six-sided cube. Each side of the cube has nine cube sides on it. The object of the game is to turn the cubes in such a way that each side has all the cubes of one particular color.
The cube that is in the center of each side is actually one big cube. It is the only one that never moves--the rest of the cubes simply rotate around it. The cubes to the left and right of the center cube (12 in total) are referred to by enthusiasts as the "middle edge" pieces. They are held to an internal mechanism that allows them to rotate both up and down. Though rotating the top or bottom row of cubes gives them the appearance of moving left and right, they do not actually move in this direction.
The corner cubes (of which there are eight total on the entire game) are held in place to the internal mechanism similar to the way the other cubes are. They have the ability to move up and down and left and right. This allows the top and bottom rows of cubes to move in these direction. By combining a knowledge of which cubes move in which directions and which cubes don't move at all, it is entirely possible for a person to arrange the game in such a way that each side of the overall larger cube has all nine cubes of a particular color on it.