A book review is a form of literary criticism or analysis in which a book is evaluated based on content, style, and merit. Book reviews are often carried out in periodicals, as school work, or online. The length of a review may vary from a single paragraph to a substantial essay that is close in length to original piece. A longer review often contains evaluations of the book on the basis of personal taste. At the other end of the spectrum are book reviews that read more like simple plot summaries.