The production of modern information and medium affects others' welfare.In consequence
of this,the externalities emerged.In general,let' s put the medium production as an example,when
there exists any deference between the interestof any private or a medium group and the interestof the
public,the externalities come into being.With the swift developing of information and medium
industries,the control of them lag behind obviously.Their ngeative externalities were not controlled
efficiently,which covers the positive externalitiesof the these industries that changing human' existing
status.Whereas,the government and medium group should strengthen the control of information
medium industries and their positive externalities to eliminate their negative ones.