Economic activity is spurred by production which uses natural resources, labor and capital. It has changed over time due to technology (automation, accelerator of process, reduction of cost functions), innovation (new products, services, processes, expanding markets, diversification of markets, niche markets, increases revenue functions) such as, that which produces intellectual property and changes in industrial relations (most notably child labor being replaced in some parts of the world with universal access to education).A market-based economy is one where goods and services are produced and exchanged according to demand and supply between participants (economic agents) by barter or a medium of exchange with a credit or debit value accepted within the network, such as a unit of currency. A command-based economy is one where political agents directly control what is produced and how it is sold and distributed. A green economy is low-carbon, resource efficient and socially inclusive.