This volume presents the first comprehensive guide to identifying antisemitism online today, in both its explicit and coded forms. Developed through years of on-the-ground analysis of thousands of authentic web comments posted by users in the UK, France, Germany and beyond, the edited volume seeks to capture all the conceptual as well as linguistic-semiotic peculiarities of contemporary antisemitism. The guide was constructed by researchers working on the Decoding Antisemitism project at the Zentrum für Antisemitismusforschung at TU Berlin, building on and extending existing basic definitions of antisemitism, and drawing on expertise in the fields of linguistics, discourse and image studies, antisemitism studies and social media studies. It sets out a pioneering step-by-step approach to identifying and categorising antisemitic content, providing guidance on how to recognise a statement as antisemitic or not; how to establish which antisemitic concept it expresses; authentic and fully-anonymised examples; and the linguistic or imagery means by which that concept or idea is communicated. As such, this volume provides an invaluable tool through which researchers, students and social media moderators can learn to recognise contemporary antisemitism, and establishes a framework which can be adapted by those working on other hate ideologies, including misogyny, racism, and Islamophobia. This is an open access book.