This book constitutes revised selected papers from the 16th and 17th International Conferences on Web Information Systems and Technologies, WEBIST 2020 and WEBIST 2021, which took place virtually in November 2020 and October 2021, respectively.The 10 full papers from WEBIST 2021 and 1 full paper from WEBIST 2020 presented in this volume were carefully reviewed and selected from originally 48 paper submissions in 2020 and 107 submissions in 2021. The selected papers contribute to the understanding of relevant current research trends in Web information systems and technologies, including deep learning, knowledge representation and reasoning, recommender systems, internet of things, Web intelligence and big data.

This book constitutes revised selected papers from the 15th International Conference on Web Information Systems and Technologies, WEBIST 20109 held in Vienna, Austria, in September 2019. The 10 full papers presented in this volume were carefully reviewed and selected from originally 87 paper submissions. They contribute to the understanding of relevant trends of current research on Web Information Systems and Technologies, including Big Data and Connected Services; Web Performance; Context-aware and Adaptive Web Applications; Human Robot Collaboration and Multi-Agent Systems; Web Application Operating Systems and Platforms; Social Media Advertising and Enhancing Purchase Intentions; Natural Language Query Interfaces and Semantic Web; and Human-computer Interaction and Dynamic Web Pages.