The book of practices of the subject of Fundamentals of Telematics offers students the first approach to computer networks in the degrees of Telematics Engineering and Telecommunication Systems Engineering. For this, this book describes in detail and quality the different sessions that form the laboratory practices, with the aim of i) reinforce theoretical concepts taught in the subject and ii) acquire new skills, abilities and competences from the study and development of real assemblies that allow the sending and receiving of data between computers. The methodology of these sessions is typical: we start with simple practices where the student will perform different assemblies for PC communication through the serial port, ending with the study of more complex scenarios, such as asynchronous communications through Ethernet interfaces, or synchronous, using ISDN technology. To carry out the practices, the student will have at his disposal all the facilities and equipment of a modern telematic engineering laboratory. As an example, the laboratory has 15 workstations composed of fully updated computers, state-of-the-art digital oscilloscopes, PODs for the realization of the configurations of the different assemblies, telephones, sniffers, etc. In addition, it also has a switchboard that integrates all the technological resources required by the set of practices and a communication infrastructure that connects the switchboard with each one of the work stations. The teaching staff that teaches are professionals of high qualification and experience. On the one hand, professor and associate professors with more than fifteen years of dedication to Fundamentals of Telematics and, on the other, young teaching assistants who contribute their youth, talent, brilliance and dynamism. Finally, the authors want to remember with affection the associate professor Felipe García, who taught in the practices of Fundamentals of Telematics for many years, contributing to its elaboration, achievement and improvement.