There are many reasons why you might want to review a book. Maybe you're looking for some help on deciding what book to read next, or maybe you just enjoy writing reviews in general. This post is designed with the latter group in mind- I'll go over some of the things that make for a good review and show examples of books from my own library that I've reviewed before.
Book reviews are often used as a way to introduce the reader or viewer to an item (e.g., book, movie) and give them insight into what it is about before they commit their time to it. They also work well in advertising new releases by giving potential consumers all that information upfront instead of making them go through the entire list for themselves when there are already so many other things vying for their attention at any given moment!

What is the book about?
In order to do a proper review, reviewers need prior knowledge of the content. Otherwise, it would be like reviewing paint without knowing what color or type you are looking at. The idea is that in order for one to properly critique something they should have prior familiarity with its contents and context so as not to miss any key points along the way
Who should read this book?
You need to figure out who's going to read your review.
The first thing you should do when reviewing a book identifies the audience that might be interested in reading it: what age group is they? What gender, ethnicity, and socioeconomic status are they? These demographic considerations will help determine how thorough of an analysis you put into each section (plot summary, character development) as well as which aspects of the writing style or themes really speak to their collective experience with this particular genre; for example, if all your readers were women between 16-25 years old then there would likely not be much discussion about any representation on race but rather more emphasis could go towards sexism.
What are the pros and cons of reading this book?
When reviewing a book, one must identify the pros and cons of reading this particular title. It is important to consider both sides in order to provide an accurate opinion on behalf of your peers. In my personal experience with Jane Eyre by Charlotte Bronte, I felt that it was worth taking time away from other distractions in life for such a well-written work about love and pain; however, there were some parts (namely near the end) that left me feeling frustrated due to lack of resolution or understanding what had happened because they occurred so quickly within only two pages before being cut off abruptly into silence.
My personal opinion on the content of this book, including whether I would recommend it or not must also be included whenever you are going to review a book. Every reviewer has their own opinion of the book they're reviewing. It's important to let your personal opinions on a novel influence how you review it so that readers can get an accurate understanding of what happened in the story and why others may have enjoyed or not liked those aspects of the story themselves.