The book entitled "Understanding the Universe of Telecommunications/ICTs" intends to help all stakeholders, including consumers, to better understand the telecommunications sector for the purposes of an optimal use, and a perspective on future developments. The document developed in the form of a presentation is composed of 9 chapters. Chapter 1, "Introduction to telecommunications and resources used " defines the concepts of telecoms and ICTs, explains the different types of electronic communications. This chapter briefly presents the 7 resources vital to the provision of telecommunications services: Radio frequency spectrum, telephone numbering plan, Internet domains, IP addresses, high points, existing infrastructures and satellite orbits. Their management and uses are briefly explained in this first part. Chapter 2 "Telecom/ICTs Environment" deals with the framework for the operation of the sector. It presents, among other things, the different stakeholders of the chain, the ecosystem, the legal and regulatory aspects, and the standardization of telecommunications. The telecommunications Services and their uses are studied in the third chapter. The principles and modes of operation of the major services are presented in a simplified manner. The fourth part presents techniques and technologies used to design, develop and provide telecoms services. The concept of "network" is succinctly developed. Chapter 5 is dedicated to telephony. It reviews the different techniques and technologies related to fixed and cellular telephony. The different services associated with telephony as well as the means of access are presented there. Chapter 6 is devoted to "Sound and television broadcasting". The techniques and means of access to radio and television are presented. The need for and the process of transition from analogue television to digital television are explained in this chapter. Chapter 7 "Computing and the Internet" provides the basic notions relating to computing and the Internet. It studies mostly the techniques, technologies, services and means of access to the Internet. The economic aspects of the telecommunications sector, which is the second world economy, are discussed in chapter 8. Chapter 9 deals with the use of telecommunications to manage natural disasters. The reader of the book will have an overview of the telecommunications/ICTs sector, and will have practical information for a better use of derived services. This document can generate among the young people interests and vocations for telecommunications and ICTs, the foundation of the information society in accelerated construction.