Thixomoulding of Magnesium based alloys has been the commercially leading semisolid casting process. Recent developments of semisolid casting of Aluminum-based alloys show great promise. The current treatise elaborates on the fundamentals of semisolid casting as well as on different process routes and methods. These process routes and methods have different benefits compared to conventional high-pressure die casting. Three different semisolid casting processes for aluminum and their capabilities and applications are discussed. In the end, design guidelines are given for design of semisolid casting.