Stratification refers to the gaps in resources both between nations and within nations. While economic equality is of great concern, so is social equality, like the discrimination stemming from race, ethnicity, gender, religion, and/or sexual orientation. While global inequality is nothing new, several factors make it more relevant than ever, like the global marketplace and the pace of information sharing. Researchers try to understand global inequality by classifying it according to factors such as how industrialized a nation is, whether a country serves as a means of production or as an owner, and what income a nation produces.
Modernization theory and dependency theory are two of the most common lenses sociologists use when looking at the issues of global inequality. Modernization theory posits that countries go through evolutionary stages and that industrialization and improved technology are the keys to forward movement. Dependency theory, on the other hand, sees modernization theory as Eurocentric and patronizing. With this theory, global inequality is the result of core nations creating a cycle of dependence by exploiting resources and labor in peripheral and semi-peripheral countries.