This collection presents the extended abstracts of posters from the 25th International Conference on Human-Computer Interaction, HCII 2023, exploring a wide array of contemporary topics in the field. The conference, held in Copenhagen, Denmark, in July 2023, gathered 1578 papers and 396 posters, with the poster contributions organized into five thematic volumes. These volumes cover crucial areas such as HCI design methodologies, multimodality, user perception, ethical considerations, user experience, and technology acceptance. Further sections delve into technologies supporting health and wellbeing, design for all and accessibility, and interactive technologies for aging populations. The collection also addresses interacting with data, learning technologies, cultural heritage, social media, eGovernment services, eCommerce, intelligent environments, and advancements in automated vehicles and extended reality applications, including AI technologies in HCI.

This multi-volume set, comprising extended abstracts from the HCII 2023 conference, offers a comprehensive snapshot of current research in Human-Computer Interaction. The sheer volume of contributions, carefully reviewed and selected, indicates a robust and active field of study. The organization into thematic parts suggests a structured approach to presenting diverse research findings, catering to specialists across various HCI sub-disciplines. The inclusion of topics ranging from theoretical design to practical applications in health, accessibility, and emerging technologies like XR and AI, highlights the expansive and evolving nature of HCI research.