In a classic Rubik's cube, each of the six faces is covered by nine stickers, each of one of six solid colors: white, red, blue, orange, green, and yellow. In the currently sold models, white is opposite yellow, blue is opposite green, and orange is opposite red, and the red, white and blue sides are ordered in a clockwise arrangement. However, on early cubes, the position of the colors varied from cube to cube. What makes it work is an internal pivot mechanism that enables each face to turn independently, thus mixing up the colors. For the puzzle to be solved, each face must be returned to have only one color. Similar puzzles have now been produced with various numbers of sides, dimensions, and stickers, not all of them by Rubik.
Although the Rubik's cube reached its height of mainstream popularity in the 1980s, it is still widely known and used. Many “speedcubers” continue to practice it and other twisty puzzles and compete for the fastest times in various categories. Since 2003, the World Cube Association, Rubik's cube’s international governing body, has organized competitions worldwide and kept the official world records.