To understand how mass communication is necessary for both individual and society, it's helpful to look at communication in a historical context. It has developed dynamically over time, increasing in complexity and meaning. Contemporary modes of communication can be understood better by studying the stages of communication that have led up to them. These stages include signs and signals, speech and language, writing, and printing.
The study of mass communication has produced several schools of thought that attempt to explain its origins and predict the future of current practices. For instance, "structural and functional" theories focus on the rules, traditions and institutions of a society, while "interactionist" theories look at the ways different types of people interact within a society. "Interpretive" theories study how people think of their own experiences while "critical" theories look at how and why certain groups of people use communication to control other groups.
One approach to studying mass communication is to look at how the information is distributed. Methods include publishing, broadcasting and digital communications, and can utilize mediums as sophisticated as the Internet or as basic as graffiti on a brick wall. The idea is to make sense of the journey of the message, from sender to receiver. What is the purpose of the message? What is the intended outcome? How and why does the sender choose which medium to use? Because influence often comes with affluence (wealth and access to resources), understanding how information is distributed means also about looking at how different classes relate to one another.
Another approach is to look at the effects of communication -- specifically its ability to persuade or manipulate how people think and what they talk about. Rhetoric (the study of persuasion), philosophy and psychology all intersect with communications studies, in that they explain why particular messages are chosen and who the messages benefit the most. In contemporary society, it is also important to look at commercialism, politics and celebrity culture when studying mass communication because in many cases these elements are now inseparable.