What is the Kosour: distinguishing features

It is worth saying that the Kosour is not only the name of the knight of epics, but also an element of one of the existing varieties of stairs. Actually, Kosour is an inclined beam on which the steps will be based. There are also stairs on bowstring and, moreover, on Boltsa. As for the style of the stairs, in the general case it should depend on the style of the interior, the taste of the owner and, moreover, the volume of rooms.