Mail two identical résumés to the same employers, change only the name at the top, and the phone may ring far more often for one of them. Nothing about the applicants differs. Something about the society reading the page does. Sociology is the discipline that notices patterns like this one: the rules nobody wrote down, the advantages nobody chose, the ties between strangers that decide who hears about a job. It started in the nineteenth century as an attempt to understand a world being remade by factories and cities, and it still asks the same restless question: what holds people together, and what pulls them apart?

You will meet the thinkers who founded the field, from Durkheim counting suicide rates to Du Bois going door to door in Philadelphia and Jane Addams mapping a Chicago neighborhood. Along the way you will learn to see your own life as part of larger patterns without losing sight of the choices you make within them. By the end you should be able to look at a news story about crime, schools, housing or work and ask the questions that separate a private misfortune from a public problem, and to judge whether the evidence behind a claim about society can bear its weight.