In modern Western societies, social stratification is defined in terms of three social classes: an upper class, a middle class, and a lower class; in turn, each class can be subdivided into an upper-stratum, a middle-stratum, and a lower stratum.

As discussed in later chapters, sociologists break the study of society down into four separate levels of analysis: micro, meso, macro, and global. The basic distinctions, however, are between micro-level sociology, macro-level sociology and global-level sociology.

It is common to divide these levels of analysis into different gradations based on the scale of interaction involved. As discussed in later chapters, sociologists break the study of society down into four separate levels of analysis: micro, meso, macro, and global.

Societies are organized on many levels: individual, families, clans, tribes, nations, states. Each level depends on the maturity and success of prior levels. Face-to-face levels are personal and larger impersonal levels employ bureaucracies and social institutions that interrelate analogous to the organs in the human body.