This timely book examines the growing importance of hashtags both in online culture and within our digital society. Conducting a comparative analysis of legal strategies within the EU, Germany, and the United States, it aims to ascertain whether a fair balance currently exists between freedom of expression and competition in the treatment of hashtags as trade marks. Nazanin Aslani firstly introduces a novel taxonomy of hashtags, highlighting their multifaceted functions, which goes beyond their commercial value to encompass their expressive, communicative, and organisational aspects. The book then highlights the need for a deeper understanding of hashtag functions, arguing that this lack of understanding has led to mischaracterisation by courts and registries, which in turn has led to contradictory case outcomes. Featuring an extensive analysis, this book advocates for strong fair use defences to maintain a balance between protection and free expression, competition, and internet regulation and deregulation. Providing a unique focus on this evolving subject, Hashtags and Trade Marks will be an excellent resource for academics of comparative trade mark, unfair competition and intellectual property law. Practitioners, policy makers and in-house counsel will also benefit from this book to fill in knowledge gaps surrounding hashtags and provide solutions for organisational devices used as trade marks yet to be developed.