Measuring globalization is no easy task, as the reader learns in the first section. However, economists – especially international economists – have long studied the process of globalization. To make issues manageable, economists have tended to focus on international trade and factor flows, a framework used by Freeman. Trade refers to international flows of goods (say, computers) or services (say, providing a warranty on your computer). Factor flows include capital flows (either the physical movement of a machine from one nation to another or financial savings across borders) and labor flows (immigration). Thus, people (or labor) flows are just one of four important channels – and not the only channels – through which globalization occurs, that is, through which the world becomes more interconnected.