This is an introductory course in computer networks. During the course, students will learn the fundamental principles and techniques that constitute the basis for the modern computer network design. All relevant levels of application will be considered and explained from Personal Area Networks to the Internet considering the most relevant technologies involved. The hardware and software architectures involved in the multilayer OSI reference model structure will be described as well as the most important communication protocols. The basic conceptual elements of network security will be introduced in the final part of this course.