There is, in general, no doubt regarding the ethical and human behaviour aspects of the research work of any type. The researchers are thought of working for society and are low paid. However, in the practice of science and technology, they should work, first of all, for system designers who need their support in designing, developing and implementing the systems under investigation. Unfortunately, this is not a popular case in the area of Information and Communication Technology (ICT), where the support of the system and network researchers for the system and network designers, developers and operators is very limited. Considering that, the team of authors of the book (the team) decided to present the design experiences gained during designing, implementing and operating some line of the computer systems and networks in Poland (the country). The country was selected purposefully: Due to the political reasons, various embargos were imposed on the importation of modern equipment and methods of the computer industry, and the team needed very severely good support from the researchers to fulfil the design and development tasks successfully. However, in the ICT domain, which is a relatively new study and, thus, needing the significant support of science in every country, this support was a minute one in practice. In well developed countries, possessing a surplus of hardware and software components, the need for the support was also observed but could be bypassed through using a surplus of supplies or by learning from the design errors. This bypass was much less available in the country in severe economic conditions and the political conditions of the so-called Cold War. The objective of this book is to present the line of the ICT systems and networks under design and operation from the late 1960s and finishing when this book was written, and to present the requirements for the system and the basic support available from this science. The research aspects under consideration were, first of all, the performance evaluation and, for the systems of the 21st century, the robustness evaluation, with the system designers, implementers and operators being the ideal audience.