The Macionis text used at IUS defines sociology as "the scientific study of human society." Another text defines sociology as "the systematic study of social behavior and human groups." These and similar one sentence descriptions of sociology are based on two key notions:
Our theories and validating methods must comply with the rules of formal logic and empiricism. The scientific method is a proven and powerful tool for analyzing phenomena. While the specific tools will vary from one scientific area to another, the basic method is always the same. Your theories must be tested against observational data. For more on the methods of sociologists.
Sociologists study coordinated behavior. We examine groups and societies and how people within them organize and coordinate their behavior. Our focus is on the relationships between individuals not on the individuals. For some people this is a difficult concept. It is much easier to think in the other direction. We recognize we are made of parts - legs, internal organs, nerve and fluid systems, millions of cells and billions of atoms. When it comes to looking back in the other direction and seeing ourselves as parts of a larger system of interrelated parts, it is natural to have some difficulty. We like to think of ourselves as individuals making our own decisions and caring for ourselves independent of the actions of others.
In reality, it is years before we are even potty trained and can feed ourselves without assistance. Without help all human infants would die from exposure, starvation or become food for other species. While there are many species that organize and coordinate some of their behavior no species coordinates behavior to the extent we do. I doubt very few people reading this have ever eaten even one meal without help from others - probably thousands of others. If you don't believe me, think about what you ate at that meal you made all by yourself. Did you have help?
Humans form networks or systems with other human beings for food, shelter, reproduction, protection and entertainment. On a micro or individual level, we use facial expressions, hand gestures and language to coordinate our actions and pass information from one brain to another. On a macro or larger societal level, we coordinate our behavior through families, schools, corporations, gangs, religions, nations, teams and other social organizations. These are the things sociologists study.