In order to fulfill its role and mission in promoting the statistical knowledge of society and contributing to the national statistical system of Iran, the Statistical Research and Training Center, in addition to implementing research projects, producing scientific articles, and holding short-term practical training courses, has on its agenda the writing and translation of books related to the topic of official statistics. Given the importance of official statistics in the country, as well as the existence of an optional course in official statistics in the curriculum for statistics students in universities, as well as the approval of the official statistics major at the master's level by the Supreme Council for Educational Planning of the Ministry of Science, Research and Technology in 2017, and the admission of students to this major since 2018, it is very important to prepare course materials for this major. Currently, the lack of a reference book related to this topic is clearly evident in the country's scientific community. It is expected that the publication of this book can significantly fill the existing gap. The present book outlines the concepts, principles, and theoretical foundations of official statistics and aims to familiarize readers with the concepts related to official statistics. The authorship of this book is attributed to Dr. Hamidreza Navabpour, Gholamreza Izadi, and Ms. Mohaddeseh Safakish, and we hereby express our gratitude and appreciation for the efforts of these esteemed individuals. Dr. Zahra Rezaei Ghahrudi also reviewed the book, and her efforts are hereby acknowledged and thanked. We kindly request all esteemed readers and connoisseurs to share their opinions, which will not only enrich this book but also assist us in achieving our desired scientific objectives.