Information is not knowledge, knowledge is not wisdom, wisdom is not truth

In this contribution to the special issue of the International Journal of Human-Computer Studies on Knowledge Acquisition I will give a view on the evolution of concepts related to knowledge during the last 25 years and will briefly look into the future. The concepts include knowledge acquisition, knowledge engineering, knowledge management, knowledge level, knowledge retrieval, knowledge modeling, knowledge protection, knowledge retention, knowledge deletion and knowledge privacy. This contribution is a reflection on the theme Knowledge Acquisition based on my experience from 1987 when I started working in this area. (C) 2012 Elsevier Ltd. All rights reserved.