Stone Slab

Steps are blocks, found in Survival when destroying Coal or crafted in Indev, Infdev, or Alpha using three cobblestone. Step blocks were formerly called stair blocks until a new stair block was added. Steps form a half block and can be walked up by the player without the need to jump. Placing two steps on top of one another makes it a full block and breaking it will only yield one step instead of the two used to place it.

Despite the fact that Sneaking gives a player an apparent height of 1.5 blocks, a player can't walk over a single step with only a single empty block above it even while sneaking.

Crafting
A Step is made from three cobblestone arranged in a horizontal line. Obviously, a workbench is required to make a step.

Trivia

 * Single-steps will destroy gravel and sand blocks that fall onto them.
 * Single-steps affect lighting and liquids in the same manner full blocks do.