The document defines an electronic book as a book-length digital publication that can be read on computers or electronic devices. It notes that e-books can be used by people of all ages and backgrounds, and that electronic copies of educational and fiction books are popular. Some advantages of e-books are that they save trees, can hold multiple books, are portable, and don't take up physical space. However, e-books also have disadvantages like technological issues, eye strain, limited selection, and fragility.