Demography is the most basic condition for regional development. Without residents, there can be no municipalities, no local institutions and no sustained economic activity. The size, spatial distribution and composition of the population shape the conditions under which development takes place across regions. In the Nordic context, where municipalities and regions have extensive responsibility for welfare services, the age structure is particularly important. The balance between children, working-age adults and older residents affects not only demand for public services, but also the tax base and labour supply that sustain them. Changes in population size and migration patterns influence municipal finances, planning capacity and the long-term viability of communities, making demographic trends a key driver of regional development.