Este libro aborda la problemática global de la Seguridad Informática y la Protección de Datos, contemplando aspectos técnicos, factores humanos y organizativos, y cumplimiento del entorno legal en siete bloques: (Description in English below). - Principios básicos de la Seguridad de la Información - Vulnerabilidades de los sistemas y redes informáticas. - Aspectos relacionados con la identificación y autenticación de usuarios en sistemas informáticos. - Principales sistemas y técnicas criptográficos. - Aspectos técnicos para implantar medidas de seguridad en redes de ordenadores. - Aspectos relacionados con la seguridad en el uso de servicios de Internet. - Aspectos legales y normativos que afectan la Seguridad Informática. This book addresses, from a global point of view, the problems of Computer Security and Data Protection, considering technical aspects, human and organizational factors, as well as compliance with the legal environment. For this, reason the content of this work has been structured in seven large blocks: - The first part presents the basic principles of Information Security in organizations and computer networks, describing the elements of Security Policies, Plans and procedures, risk analysis and management, as well as certification according to standards. like those of the ISO / IEC 27000 family. - The second part studies the vulnerabilities of computer systems and networks, the most common threats and types of attacks. Incident Response Plans and Business Continuity Plans are also analyzed. - A third part is devoted to aspects related to the identification and authentication of users in computer systems, including the study of the latest biometric systems. - The fourth part describes the main cryptographic systems and techniques, as well as some of their applications to improve the security of computer systems and Internet services, analyzing the characteristics of the electronic DNI or electronic invoice. - The fifth part focuses on the technical aspects to implement security measures in computer networks, analyzing the role of devices such as firewalls, intrusion detection systems (IDS) or proxy servers. Likewise, the study of security in virtual private networks and wireless networks is addressed. - In the sixth part of the book, aspects related to security in the use of the main Internet services, the development of online payment methods, and how to deal with problems such as spam, phishing or protecting the privacy of citizens on the Internet. - Finally, in the seventh part, various aspects related to the legal and regulatory environment that affect Computer Security are analyzed: the fight against Computer Crime, the protection of Personal Data or the Control of Contents, among others.