This book is on digital audio visual (AV) preservation. It highlights the concept, theory and practical issues of the long term digital AV preservation. The book is based on a European Union's Presto4U project that deals with creation of software to facilitate matching of AV preservation 'Needs' with required 'Tools'. This qualitative and quantitative study covered fourteen organizations (libraries, museums, and research institutions) belonging to several European countries as a contributor of European Union's Presto4U project.Three communities of practice namely Research and Scientific Collections; Video Production and Post Production; Learning and Teaching Repositories have provided their needs for analysis.Open Archival Information System (OAIS) reference model is used as theoretical framework because it provides complete guide on how to preserve a digital document for long term.In short, the study has evaluated and discovered the knowledge schema usefulness to express the needs of communities of practice but data needs to be collected in a manner it easily fits into the structure of knowledge schema. I hope you will like the book.