Redstone Dust

Redstone is for circuitry. This is done by placing it on the ground to create redstone wire. It is also for crafting and brewing potions. Redstone can be obtained by mining redstone ore with an iron pickaxe or better, by trading with priest villagers, or by killing witches. Redstone can be crafted into numerous redstone components.

Smelting
Redstone is able to be obtained by smelting redstone ore, but this is an inefficient way to obtain redstone. Redstone ore blocks can only be obtained with a Silk Touch pickaxe, and smelting redstone ore only produces one item of Redstone, while placing the block and mining it can produce 4-5 items of redstone (up to 8 with a Fortune tool).

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's shape is shared by glowstone dust, 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 on the right-hand side of the cave, you can find your way out again by keeping the placed redstone 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 to make a trap.
 * In the Pocket Edition, redstone ore exists, but if you try to mine it, it will not drop any redstone.
 * The electronic and magnetic qualities of Redstone may allude to copper, which is reddish-orange in colour and used in generators, electromagnets, motors, coils and wiring; or less likely to 2 real life forms of Iron Ore called hematite and magnetite which are reddish-brown and black in colour, respectively, and both have properties that allow use in magnetic data storage and for primitive magnets.
 * Programmable tiles were originally supposed to be added in an expansion pack called Dungeons and Levers after the release.
 * Mojang were originally going to add gears to Minecraft instead of redstone, but then decided against it.