The PSOC is a statistical classification of the different occupational groups of the working population, including the military workforce.

It serves the needs of statistical operations and activities, such as censuses and surveys, job placement and recruitment services, vocational training and guidance, immigration purposes and related activities.

It also provides a basis for manpower/educational planning and policy decision-making.

For classification purposes, an occupation is defined as the "type of work a person does to earn his living." What a man does for a living defines the occupational classification group where he belongs irrespective of the industry in which he is employed. In the case of a person with dual activity, three criteria may be used to determine the principal activity he is engaged in: time, skill (where applicable) and income.