Public Health in America goes into greater detail regarding the services that are needed to assure that the core functions of public health identified by the Institute of Medicine are carried out. The change in terminology from core functions to essential services has been confusing to some, however. This ‘wheel’ was developed to illustrate 3 things:

-the core functions and the essential services that make them up are a continuous, rather than a linear process

-the essential service of research does not stand alone, but informs all of the other services

-the entire system must be managed, though this is not itself an essential public health service to the community