What is the definition of public health?

Definitions of Public Health Practice
Use Chapter 1 in your Introduction to Public Health text to answer the following questions:

What is the definition of public health? Remember to cite your source.
How do the three core functions of public health—assessment, policy development, and assurance—compare and contrast to the functions of health care?
What are the six disciplines of public health?
How are these disciplines used to accomplish the core functions?
Based on your personal or professional experience, which one of the six disciplines interests you the most? Why?