The emergence of Social Media Plaforms, and the rise of Influencers, have created a new online ecosystem known as "the beauty community". This phenomenon has completely disrupted the beauty industry and revolutionized the consumer's decision journey in this sector. The driving force of the beauty industry - millennial consumers - nowadays spends most of its time on social media platforms. Trends and opinion leaders are the main source of information, to which they award a previously unrecorded amount of trust.This book will, therefore, examine the current literature about the subject, by highlighting how Social Media Influencers and Social Media Trends are changing and shaping the industry. Firstly, it provides theoretical support to the allegation that, in order for a beauty brand to increase revenue streams, gain competitive advantage, market share and customer loyalty, Social Media and Influencer marketing cannot be ignored. Secondly, by focusing on millennials' purchase behaviour, this book provides an empirical analysis of how the preferred sources of information, in which consumers allocate trust, impact perceived brand image and the consequent purchase intention.