The five-volume set CCIS 1832-1836 contains the extended abstracts of the posters presented during the 25th International Conference on Human-Computer Interaction, HCII 2023, which was held as a hybrid event in Copenhagen, Denmark, in July 2023. The total of 1578 papers and 396 posters included in the 47 HCII 2023 proceedings volumes were carefully reviewed and selected from the 7472 contributions.The posters presented in these five volumes are organized in topical sections as follows: Part I: HCI Design: Theoretical Approaches, Methods and Case Studies; Multimodality and Novel Interaction Techniques and Devices; Perception and Cognition in Interaction; Ethics, Transparency and Trust in HCI; User Experience and Technology Acceptance Studies.Part II: Supporting Health, Psychological Wellbeing, and Fitness; Design for All, Accessibility and Rehabilitation Technologies; Interactive Technologies for the Aging Population.Part III: Interacting with Data, Information and Knowledge; Learning and Training Technologies; Interacting with Cultural Heritage and Art.Part IV: Social Media: Design, User Experiences and Content Analysis; Advances in eGovernment Services; eCommerce, Mobile Commerce and Digital Marketing: Design and Customer Behavior; Designing and Developing Intelligent Green Environments; (Smart) Product Design.Part V: Driving Support and Experiences in Automated Vehicles; eXtended Reality: Design, Interaction Techniques, User Experience and Novel Applications; Applications of AI Technologies in HCI.