Sociolinguistics is the study of language's relation to society. Ideas Sociolinguists would study would include those such as; Why and how do we speak differently to certain groups (to your boss versus to your friends); what signals do we show or interpret to determine how we speak (when do bilinguals switch between languages or how do we know to change a subject?); how do men and women speak differently; how does knowing more than one language affect your speech patterns; and many many more.
The scope of Sociolinguistics is to determine who says what to whom, when, where, how, and why. How do you speak to your friends in private and why do you speak differently to your boss or parents? Through studying the scope of Sociolinguistics, one can even determine a person's social position, education, background, setting, sex, age, and much more. The scope of Sociolinguistics is very broad but has an incredible impact on language and the different varieties we have.