Piston is one of the cornerstone components of redstone engineering. It is crafted from three planks on top, four cobblestone on the sides, an iron ingot in the centre and a redstone dust at the bottom. When the piston receives a redstone signal, its head extends one block forward, pushing whatever is in front of it up to twelve blocks deep. When the signal cuts out, the head retracts — but the pushed block stays in place. That single behaviour is the basis for hidden doors, drawbridges, automatic farms, flying machines, and most non-trivial redstone contraptions.

Not everything can be moved: obsidian, bedrock, furnaces with contents, and any block with a tile entity (like chests in Java Edition) resist piston push. Pistons can be aimed in all six directions, including downwards, and they propagate quasi-connectivity in Java Edition — a quirk that hardcore redstone players exploit for compact circuits. For applications that need the block to come back, the sticky variant is the right tool; the regular version is preferred whenever release timing matters.