With concrete work, screeding is the action of flattening poured concrete into a smooth, flat layer prior to finishing the surface.
Screeding is only the first step in finishing concrete, and it is not intended to produce a completely smooth final surface. Screeding fills in large gaps and removes high spots in the concrete material being installed. The final finish will be created by floating the concrete with one or more smooth-faced tools that are designed to draw up fine aggregate and cement to the surface of the slab. For large slabs such as driveways or garage floors, the surface is floated with a large tool known as a bull float.
Smaller wood and metal hand floats are used for sidewalks and other surfaces, but whatever tools are used, they can create a smooth surface only if the concrete has first been screeded to create a uniform layer.