In the US screed is a flat board, or a purpose made aluminium tool, used to smooth concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

 after it has been placed on a surface. Also used to assist in leveling the application of plaster.

In the UK, screed is a thin, top layer of material (traditionally sand and cement), poured in situ on top of the structural concrete or insulation, on top of which other finishing materials can be applied, or it can be left bare to achieve an effect similar to that in buildings by Tadao Ando

Tadao Ando

is a Japanese architect whose approach to architecture was once categorized by Francesco Dal Co as critical regionalism. Ando has led a storied life, working as a truck driver and boxer prior to settling on the profession of architecture, despite never having taken formal training in the field...

. It is becoming more common to use "self levelling" poured screeds which use materials other than cement as their binder.

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