A sale is the act of selling a product or service in return for money or other compensation. It is an act of completion of a commercial activity. wikipedia.org

Sales promotion includes several communications activities that attempt to provide added value or incentives to consumers, wholesalers, retailers, or other organizational customers to stimulate immediate sales. These efforts can attempt to stimulate product interest, trial, or purchase. wikipedia.org

An electronic book is a book-length publication in digital form, consisting of text, images, or both, readable on computers or other electronic devices. wikipedia.org

Digital marketing is an umbrella term for the marketing of products or services using digital technologies, mainly on the Internet, but also including mobile phones, display advertising, and any other digital medium. wikipedia.org

A review is an evaluation of a publication, product, service, or company such as a movie (a movie review), video game, musical composition (music review of a composition or recording), book (book review), a piece of hardware like a car, home appliance, or computer; or an event or performance, such as a live music concert, play, musical theater show, or dance show. wikipedia.org

Marketing strategy is a process that can allow an organization to concentrate its limited resources on the greatest opportunities to increase sales and achieve a sustainable competitive advantage. wikipedia.org