Recent applications of Knowledge Organization Systems: introduction to a special issue

This special issue of the International Journal of Digital Libraries evolved from the 13th Networked Knowledge Organization Systems (NKOSs) workshop held at the joint Digital Libraries conference 2014 in London. The focus of the workshop was 'Mapping between Linked Data vocabularies of KOS' and ‘Meaningful Concept Display and Meaningful Visualization of KOS’. The issue presents six papers on the general theme on both conceptual aspects and technical implementation of NKOS. We dedicate this special issue to our long-term colleague and friend Johan De Smedt who died in June 2015 while we were editing the special issue. (author's abstract)