Lever

A Lever is one of the four Switches currently in the game. Levers - like the Stone Button - can be connected with Redstone (Wire) to be operated far away from the target block. You can place levers on every non-transparent block.

Crafting
Levers are made from a stick and a piece of cobblestone, and can be placed on both walls and floors.

The Lever cannot be hung from the ceiling and cannot be placed on certain objects.

Power
Levers differ from buttons in that the charge they provide is stable - once clicked a lever will remain on or off until clicked again. Clicking a lever also causes a visual change as the shaft of the device moves from one side to the other. Their stable nature makes levers well suited to controlling devices that need to remain in one of two states for an indefinite period, such as minecart tracks or locking mechanisms in advanced circuits.

When placed on the side of blocks, up is OFF and down is ON. On the top of blocks, ON is south or west, OFF is north or east.

Trivia

 * The lever along with wall mounted Torches, flowing Lava and Water, sloped rails and Snow golem's arms are the only surfaces in Minecraft that are not parallel or perpendicular to the ground.
 * The rotation of levers placed on the top of blocks is decided randomly and not influenced by the rotation of the player.
 * Anything powered by a single Redstone Torch, such as a Powered Rail block can be replaced with a Lever. This is useful if you are low on Redstone.
 * Levers cannot be placed on snow. They also cannot be placed on Ice.
 * In Quenya, the translation for lever is still 'Mechanic Penis.' As of 1.2.3, Mojang is yet to fix this translation.

Hebel Lever/es Levier Lever/ko Schakelaar Dźwignia Рычаг 拉杆