This book inaugurates a series of discussions on what is permanent in the original thinking of the UNL – Universal Networking Language – and the changes that have been introduced during its development. The purpose of the book is to highlight the UNL’s fundamental principles that remain as integral as they were when they were first formulated several years ago, while showing how their materialization has evolved over time, following the advances in Linguistics, Knowledge Engineering and Information Sciences. The fundamental and unchanged principles of the UNL are: The idea of an artificial language that is able to describe the universe similar to any human language; The idea of a language that, though artificial, is made up of lexical, grammatical and semantic components in the same way as any natural language; The idea of a language that can represent information and knowledge independently of natural languages; The idea that it is a language for machines, and enables human-machine interaction in an intelligent partnership. For more than a decade, eminent linguists, IT developers, NLP scholars worked together on the materialization of the “idea” of the UNL. At the start, they adopted set specifications on the formalism of the UNL that were followed by all of them. As their work progressed, they gradually realized the need for adjusting some of the initial specifications and for introducing new ones. These specifications concern three basic components of the UNL linguistic structure: the “Universal Words” (UWs) which constitute the vocabulary of the UNL; the “Relations” that describe semantic functions between two UWs; and “Attributes” that describe circumstances under which UWs and “Attributes” are used.