The study of various groups within a societal structure that determines the reasons why those groups exist within said societal structure. Simply put, sociology tries to make sense out of why people do what they do in the society they live in, but it's not all-inclusive, nor does sociology explain every single detail. It's an educated guess.
Karl Marx believed very firmly in the conflictive theory of sociology, and that is because he was very communistic in his thinking, whereas, my take is more functionalist, because I believe that people are in this society to serve various functions, and those functions they serve are overall better for the society as a whole, and it brings the person contributing a sense of greater satisfaction knowing that they have contributed to a greater good.
I am a soc. major and I am focusing on the prison system and more specifically drug offenders. I believe treatment whould be the first option seeing as it is less espensive than the prison system and has shown to be more effective because of less repeat offenders.