Social networking: online profiles vs. real-life personality

I've always been interested in who people are, but with the rise of new media, understanding people's personalities is complicated by a completely different outlet for people to express themselves. With online social profiles, people have more control (or sometimes, much less) over what others see about them and can build a profile that may be very different from how they are perceived face-to-face. One example in my life that I've seen is the difference in how people use Instagram and Snapchat--two image-sharing mobile apps, one that documents personal history and one aimed to be momentary. I'd like to research how social networking grew since its inception and how different iterations (including different websites, design evolutions, uses of social networks) contribute to building a person's online profile. Another area of research may include discussion forums or media comment sections, in which people interact differently than they would in real-life because they are online. At the end of this project, I'd like to learn more about the extent (if at all) to which people use social networking to craft the image and reputation they want to portray in real life.