The Factors of Production (FoP)!

There are four factors of production: land, labor, capital and enterprise. Land includes all productive inputs in the land, on the land and above the land, including minerals, oil, crops, and iron ore from mountains. Land is paid in rent. Labor includes all productive inputs in the form of people as workers. They receive wages. Capital is the capital stock of the economy, including all the machines, factories, even pens and pencils. Firms use capital to make other goods and services in the production process, and it's paid in interest. Lastly, as The Economist web site nicely describes, enterprise is the "animal spirits of humans" to combine land, labor and capital in novel ways to make g/s. Entrepreneurs are paid in profit. A country is said to have a fixed number of FoPs in the short-run, but most of the time (unless there is a devastating event like the Haitian Earthquake of 2010), productive capacity increases over time (due to factors like technological advancement and population growth). Of course, land has many fixed factors, including the physical amount of oil and gold. Unless we conquer another planet, it's all we've got!