Terminologies – the lexical components of specialized languages - emerge from theoretical and technological innovation: new scientific insights and novel tools enrich the conceptual and practical environment of the specialists, and in the process expand their vocabularies. But these forces apply just as well to terminology as a discipline, i.e. to the linguistic analysis of terminologies and their practical description in a lexicographical format: changes in the theory and practice of terminological studies correlate with developments in their scientific and technological environment. The exceptional importance of the current Handbook, which takes stock of the current state of terminological studies, can therefore be best appreciated if we see it against the background of crucial developments in the theoretical and practical environment in which the discipline operates.