The population of a nation is generally grouped into the following three categories.
(i) Children (generally below 15 years): The group of population that comes under this category is economically unproductive and needs to be provided with food, clothing, education and medical care.
(ii) Working Age (15-59 years): They are economically productive and biologically reproductive. They comprise the working population.
(iii) Aged (above 59 years): They can be economically productive though they may have retired. They may be working voluntarily but they are not available for employment through recruitment.