Now in its 18th edition, the ISWC conference is the most important international venue to discuss and present latest advances and applications of the Semantic Web, Linked Data, Knowledge Graphs, Knowledge Representation, and Intelligent Processing on the Web. At the beginning of the 2000s this research community was formed, starting with the first international Semantic Web Working Symposium (SWWS), a workshop held in Stanford, Palo Alto, held during July 30 to August 1, 2001. The following year the symposium became the International Semantic Web Conference (ISWC) series in Sardinia, Italy, and at that time the website was predicting that it would be a major international forum at which research on all aspects of the Semantic Web would be presented. And indeed, as in previous editions, ISWC 2019 brought together researchers and practitioners from all over the world to present fundamental research, new technologies, visionary ideas, new applications, and discuss experiences. It featured a balanced mix of fundamental research, innovations, scientific artefacts such as datasets, software, ontologies, or benchmarks, and applications that showcase the power and latest advances of semantics, data, and artificial intelligence on the Web.