Preface IWSW 2018 This book of proceedings contains the accepted papers of the 3rd International Workshop on Semantic Web (IWSW 2018) held in Havana, Cuba, March 07, 2018. This workshop series was launched in 2014 with the support of the Semantic Web Research Group from the University of Informatics Sciences. The IWSW 2018 was a forum for the semantic web and linked open data communities, where practitioners in industry, academia, and others interested in these topics presented theoretical and applied for research work, share experience and discuss the latest scientific results and the technology innovations around semantic technologies and linked open data. In this edition, we received research papers related to the application of the semantic web and linked data technologies to Cultural Heritage, Educational Data, Geographical Information Systems, Knowledge Management, among others. We received research papers from Belgium, México, Ecuador, United States of America and Cuba. We would like to thank the participants of the workshop as well as the Program Committee Members. IWSW 2018 Chairs Yusniel Hidalgo Delgado and Amed A. Leiva Mederos Technical Program Committee Amed A. Leiva Mederos; Universidad Central de las Villas; Cuba Juan Pedro Febles Rodríguez; Universidad de las Ciencias Informáticas; Cuba María A. Medina Nieto; Universidad Politécnica de Puebla, México Victor Saquicela; Universidad de Cuenca, Ecuador Alfredo Simón Cuevas; Instituto Superior Politécnico José Antonio Echeverría; Cuba José A. Senso; Universidad de Granada; España Iván López Arévalo; Centro de Investigación y de Estudios Avanzados; México Nelson Piedra; Universidad Técnica Particular de Loja; Ecuador Peter Wetz; Vienna University of Technology; Austria Boris Villazón Terrazas; Fujitsu Laboratories of Europe; España Carlos Buil Aranda; Pontificia Universidad Católica de Chile; Chile David Vilares Calvo, Universidad de A Coruña, España Maria Asunción Hallo Carrasci, Escuela Politécnica Nacional; Ecuador Eduardo Garea Llano; Centro de Aplicaciones de Tecnologías de Avanzada; Cuba Benjamin Fabian; Hochschule für Telekommunikation Leipzig; Germany