In this chapter we extend our applications of the economic way of thinking to international trade and finance and environmental economics, relying again extensively on supply and demand graphs. We cover international economics early in the book for a straightforward reason: international trade and finance have become progressively more important issues for business. Moveover, national economies have become integrated and interdependent to a degree not imagined just a few decades back. The business of much business has become global in scope because of technological gains in transportation and telecommunications. The extent of the integration of national economies has been dramatized in recent years through the rapid spread of the financial crisis, attributable to the bursting of the housing price bubble and the collapse of the market for mortgage-backed securities, that became evident in the United States's banking system in late 2007, only to cause a growing list of major banks around the world to hover on the brink of bankruptcy in 2008 and 2009.