Este libro presenta los conceptos básicos de las redes de ordenadores, protocolos de comunicaciones, medios de transmisión, dispositivos de interconexión, redes de área local, redes inalámbricas, redes privadas de datos, funcionamiento de Internet, las distintas tecnologías de acceso, entre otros temas (Description in English below). La segunda edición del libro además analiza los nuevos servicios y aplicaciones populares: Voz IP, televisión y streaming de vídeo, servicios basados en la movilidad o el papel de las redes sociales. El objetivo ha sido acercar los conocimientos técnicos necesarios y ofrecer una panorámica actualizada de las distintas tecnologías disponibles en el mercado. This book presents the basic concepts and main characteristics of computer networks, communication protocols, transmission media, different interconnection devices (hubs, switches, routers ...), local area networks, wireless networks (Wi-Fi, Wi-Max, Zigbee ...), private data networks, the operation of the Internet, the different access technologies (ADSL, fiber optics, LMDS, PLC ...), classic services and new advanced services offered by the Internet, security in computer networks and the fundamentals of cryptography, among other topics. New services and applications that have become popular in recent years are also analyzed in detail: IP voice, television and Internet video streaming, services based on mobility or the prominent role of social networks ( Facebook, LinkedIn, Twitter ...). The authors' objective has been to bring together the necessary technical knowledge and offer an updated overview of the different technologies available on the market, evaluating the advantages and disadvantages of each one, as well as their possible interest and application, both personally and professionally. and business.