Industry, in its broadest sense, includes all economic activity, but for convenience commentators divide it into three sectors: primary, secondary and tertiary. Primary manufacturing involves harvesting natural resources; secondary, manufacturing; and tertiary, the service industries. All these elements make up Canada's industrial system, which has become increasingly complex over time. Canada is considered a “developed” country in that it has, as part of its economy, a developed industrial base. (See also Economic History; Regionalism; Regional Economics; Technology.)