Rolling is a metal working procedure, in which, a metal is rolled between two rollers.  Compressive force is applied on the material and the thickness is reduced along with an alteration of the grain structure. 

Rolling results in a reduction of the thickness and a hardening of the material.  Cold rolling is done below the recrystallization temperature while hot rolling is done above the recrystallization temperature. 

Hot Rolling improves the grain structure and makes it more uniform.  It also removes porosity and other casting defects from the metal. 

Rolling is used to produce metal sheets.  Metal can be passed through consecutive sets of rollers to progressively reduce the thickness.  Metal foils used for wrappings are also produced by rolling. 

Rolling can also produce shapes such as T and L shaped profiles