Primary prevention is the term used for activities designed to stop people from developing a certain condition i.e. reducing incidence. Using sunscreen to prevent sunburn is an everyday example.
Taxing tobacco and alcohol is an example of a population-level activity that reduces the risk of an entire population developing certain chronic health conditions.
Primary prevention is often contrasted with secondary prevention (early detection and efforts to ameliorate disease severity) and tertiary prevention (efforts to allay disease symptoms).
The University of Ottawa provides this helpful overview of the distinction between individual- and population-level primary prevention:
Primary prevention may be aimed at individuals or at whole communities. Individual approaches (encouraging your patient to stop smoking) have the advantages that the clinician's personal contact should be motivational; the message can be tailored to the patient, and you can support him in actually making the decision to stop. But the limitation is that your advice does not tackle underlying forces driving his behaviour in the first place or the context in which his behaviour occurs (his friends may continue to smoke). Therefore, a community or population approach (e.g. via mass media advertising, increasing taxes, or banning smoking in public places) tries to change risk factors in the whole population. It is more radical and may produce cultural and contextual changes that may support individual efforts.