Redstone Dust

Redstone dust is a crafting and brewing ingredient. Redstone dust can be obtained by mining redstone ore with a iron pickaxe or better. Redstone dust can be placed on the ground to make redstone wire. Redstone can also be crafted into a redstone torch and/or a redstone repeater. These items can be used in more complex traps and redstone circuitry.

Redstone is a unique material in the game. Switches and redstone torches can provide electrical-like power to wires or objects.

Smelting
Note that the redstone ore block cannot be obtained without the Silk Touch enchantment, and that this smelting is inefficient as destroying an ore block yields 4-5 redstone dust rather than the single one smelting does.

History
Programmable tiles were originally supposed to be added in an expansion pack called Dungeons and Levers after the release.

Trivia

 * The introduction of redstone was a small step towards interactivity, and brought with it the mechanics of redstone circuits, making it possible to create circuits linked with buttons, levers, pressure plates and logic gates, which can currently be tied to things like doors, minecart tracks and TNT. It is possible, however, to connect levers, buttons and pressure plates directly to these objects, as redstone wire is not needed when switches are directly adjacent to objects.
 * Redstone dust's appearance is shared by glowstone dust and, to a lesser extent, gunpowder and sugar.
 * Another good use for redstone, as people generally accumulate too much of it while exploring natural dungeons, is to use it as a way to find your way in a cave, so that you do not get lost. By placing redstone dust on the right- hand side of the cave, you can find your way out again by keeping the placed dust on your left.
 * Redstone is also useful for making an obsidian generator. This is a bug that will likely be patched in a later update, but is currently a safe and economical way to get obsidian. By using one bucket of water and one of lava, redstone can be converted into obsidian.
 * In multiplayer, if PvP is disabled, one can still kill someone by using redstone dust to make a trap.
 * In the Pocket Edition, redstone ore exists, but if you try to mine it, it will not drop any redstone dust.
 * If a block falls onto a block with redstone applied to it (like sand or gravel), it will break the falling block and give the player the resource. This is useful when clearing out large areas of sand or gravel.