Factor of production

There are two types of factors: primary and secondary. The previously mentioned primary factors are land, labour and capital. Materials and energy are considered secondary factors in classical economics because they are obtained from land, labour, and capital. The primary factors facilitate production but neither become part of the product (as with raw materials) nor become significantly transformed by the production process (as with fuel used to power machinery). Land includes not only the site of production but also natural resources above or below the soil. Recent usage has distinguished human capital (the stock of knowledge in the labor force) from labour. Entrepreneurship is also sometimes considered a factor of production. Sometimes the overall state of technology is described as a factor of production. The number and definition of factors vary, depending on theoretical purpose, empirical emphasis, or school of economics.