Imagine a library with physical books, scanned copies, OCR copies (as pdfs generated from scans) and digital books in pdf or epub formats. If there is a demand for all OCR, pdf or epub files containing the text "Kal Chakra" he can search and retrieve such files from the hard drive or cloud location where they are stored. If there is a demand for availability of a paperbound book, the user can search the book by author, name, tags, description, etc. and see if it is available, and which shelf it is put in. He can retrieve the book from the shelf and mark the particular book copy as granted to his username. In case a user is not sure which book to rent, he can simply browse by genres, keywords, authors, languages or any other relevant fields and pick up one based on good ratings and reviews. He can rate the book himself or write a review once he has finished reading.