Various sintering theories based on two-particle model are no longer valid. Apart from this the basic properties and data of materials are also much more accurate in the present date, thus casting doubt in the previous theories. The role of electronic structure of additives in activating sintering processes has been convincingly put forth. In the field of sintering practice still a gap is apparent with the theory. Various techno-economic factors including the nature of starting powders have, of late, given good impetus in tackling this challenge.