“W3-ChaT” — WWW — Challenges and Trends (W3-ChaT 2018) The W3-ChaT workshop is focused on addressing existing challenges we are facing today on the Web (and in general on Internet). Solutions of such challenges are crucial to support/improve smooth experience of users with the Web as well as their decision making. Web challenges are strongly associated with intelligent algorithms of various kind and purpose acting as clever solutions simpli- fying many tasks such that mining users’ data and relevant data sources with associated semantics, extracting users’ contexts and predicting their interests leading to improved data providers, user ex- perience and semantics as proper knowledge representations. Workshop Program Committee Jaroslav Kuchař, ČVUT Praha Peter Vojtáš, UK Praha Ladislav Peška, UK Praha Milan Dojchinovski, FIT ČVUT Praha Tomáš Vitvar, FIT ČVUT Praha Tomáš Horváth, ELTE Budapest László Grad-Gyenge, Creo Group, Budapest András Micsik, MTA SZTAKI, Budapest Tomáš Kliegr, VŠE Praha 145