Previewing is a tactic used by readers to recollect past knowledge and set a reading goal. It encourages readers to scan a book before reading it, seeking for characteristics and information that will be useful when they return to study it in depth later. The term "preview" comes from the practice of reading part of a work (a chapter or section) before deciding whether to buy it. Readers use different methods to preview books. Some read only a portion of the book, such as a short story or chapter, while others read every page in order to get a general idea of the content. Previews are important because they help readers decide what books to purchase and what parts of these books to focus on during their studies. This can be particularly helpful for students who have a large number of books they want to read but not enough time to do so. Previews also allow them to find out if there is anything in particular they should know about a book before starting to read it. Books may include previews of other books within the same series. For example, a reader might see how another book in the series ends before reading it themselves. This helps them make an informed decision about whether to continue with the series. Previews may also contain promotional material regarding the book, such as interviews with authors or characters, or even excerpts from the text itself.