The focus of this edition is to present the subject matter in a way that can be understood easily and at the same time without missing any details. The reactive lesions are a group of relatively common lesions in the oral mucosa because they are constantly subjected to external and internal stimuli and often require biopsy in clinical practice for diagnosis. The main purpose of this book is to give an overview of frequency and distribution of oral cavity reactive lesions. My motivation for this book writing came from oni Morrison "If there's a book that you want to read, but it hasn't been written yet, then you must write it.