Together with ChengXiang Zhai, we will be giving our user simulation tutorial at AAAI’24 and WWW’24, customized to the respective audiences. The AAAI’24 edition adopts a broader perspective of user simulation for evaluating an interactive AI system and focuses more on simulation algorithms and techniques that are well connected with various sub-fields of AI, such as machine learning and agent-based systems. In contrast, the WWW’24 edition emphasizes more on applications of user simulation for evaluating Web information access systems, including click modeling and the application of simulation techniques in e-commerce.