There are too many types of licensing qualification certificates, whose institution is a kind of public administration system adopted for specifying and promoting enterprises or individuals to be engaged in commercial activities and business scope management as well as for maintaining favorable market order according to law during enterprise operating management, and the major cause is the rules and regulations that relevant state authorities issue for guaranteeing people's rights and interests so that enterprises and individuals can run and execute their responsibilities and obligations completely and legally. Enterprises shall have different requirements and application of the different qualification certificates according to different operating items. 

The implementation of license system does not only play an impotent role in promoting enterprises to enhance quality management and improve products quality, but also speed up the adjustment of industrial structure and the purification of market environment; Before they develop and build sewerage system in accordance with mandatory rules and the requirements of local competent authorities, they should make application and get the approval through legal procedures and their business operation will be under supervision. The system is conducted mostly in the form of license, owing to which it is called as license system or licensing system. In generally it includes license application, check-up, approval, supervision, termination, suspension, cancellation and some other management activities, which can be classified into plan, development, production & promotion as well as sewage discharge permission and etc. in accordance with different managed objects.