Developments in the packaging and distribution processes usually occur in four main areas: in new materials and constructions and up-dates of older ones; in developments in packaging machinery, ancilliaries and improved line efficiency; in methods of distribution, warehousing and stocking; and in improvements in management methods and control. Much of the change over the years has been triggered by the increasing use of plastics materials of all types. Not plastics alone, however, for metal, glass, paper and board and other minor materials have reacted to the competition from plastics, and frequently have utilized plastics as part of their make-up. Today there are very few packages which do not contain at least two of the major media in their construction. The other major catalyst of change has been the use of computers and robotics. The three basics of packaging - containment, protection and preservation - are important, yet they are often overshadowed by the secondary considerations of communication, selling and economy.