Czech Silesia is the name given to that part of the historical region of Silesia presently located in the Czech Republic. While not today an administrative entity in itself, Czech Silesia is, together with Bohemia and Moravia, one of the three historical Czech lands.
It lies in the north-east of the Czech Republic, predominantly in the Moravian-Silesian Region, with a section in the northern Olomouc Region. It is almost identical in extent with the Duchy of Upper and Lower Silesia, also known as Austrian Silesia before 1918; between 1938 and 1945, part of the area was also alluded to as Sudeten Silesia: a reference to the Sudetenland.
Slezsko is a former region.