The objective of this chapter is to explore how teenagers build their online identity and personal brand in social media. The text uses the results of the European project Transmedia Literacy to look at what skills teens employ to do this. The research revealed that sharing content on Instagram and YouTube is a crucial part of teenagers’ everyday life and central to their online interactions. Teens plan their online creations and when they will upload their photographs and videos. They use filters or editing tools, “comment”, “like”, and “share” their photos and videos. Social media are the tools that teenagers use to follow the lives and interactions of celebrities, peers, and strangers. Instagram and YouTube are the most significant social media platforms for teenagers, as they underpin the profiling and branding of their personal accounts. Through these platforms, they present themselves in the best possible way and work to build an online identity and personal brand.