Public health focuses upon the collective health-status of an entire population of individuals. This collective health-status must be defined wholistically, in terms of the physical and emotional health of the people within the population. This collective health-status derives from multiple factors beyond any one individual's or organization's control.

Personal health, on the other hand, is an individual matter. Personal health is the responsibility of individuals in consultation with their health-care consultants. The focus is on the health status of the individual. This is the focus of most health-care practitioners and of people seeking health-care consultation and/or treatment. Because each individual is unique (i.e., one person's medicine can be another person's poison), personal health matters often must be clarified on an individual – not a collective – basis. Each individual's own personal behaviors contribute, in varying ways and to various degrees, to their own personal health.

Professional public-health practice is where public health analysts study broad public health trends and outcomes. They design and implement strategies for protecting and encouraging public health in ways that are beyond the reach of individuals. This public health activity should be designed to include and support the personal health of the individuals involved.

In practical terms, public health practitioners have focused on identifying and defining public health problems – health problems effecting many people -- and then the sources of those problems. This can include a focus on environmental factors (for example, the presence of a virulent virus). This can also include a focus on social factors -- where and how personal behaviors, in a particular physical environment and in a social context, impact the health of other persons. For example, those who have contracted a virulent virus might be empowered to reduce the likelihood of spreading that virus to others through self-care and other behaviors to reduce exposure to others.

As in this example, public health activities or interventions often involve the consideration of the intersection between personal rights and public interests.

For another example, drinking alcohol while operating heavy equipment and/or machinery represents a (dangerous) personal behavior with very dangerous implications for the personal health of that individual as well as for the property and bodily health of any persons in that operator's immediate environment. Public health considerations have led to the formulation and enactment by public health officials of legal blood alcohol levels (usually zero) for the legal operation of heavy equipment and/or other machinery.

Professional public health practice can be funded by private- and public (governmental) organizations. These public health organizations can be locally-directed, regionally-directed, state-wide, or national in scope. International or "global" public health organization have also been formed in the attempt to understand and impact public health from a global perspective.

Definition for Public health

· an effort organized by society to protect, promote, and restore the people's health. - healthyamericans.org