Screeding is leveling and smoothing the top layer of concrete, so that it is the same height as the forms that surround it. If screeding is less than accurate, you could suffer later with cracks and divots that could make for a bumpy floor.  A good leveling job is important if you would like to maintain the life of the surface is being laid.

A screed is a flat board, or a purpose made aluminum tool, used to smooth concrete after it has been placed-casted on a surface. Also used to assist in leveling the application of plaster.

Screeding is the process of cutting off excess wet concrete to bring the top surface of a slab to the proper grade and smoothness.