The ATRIUM ATR Summer School provided an in-depth approach to automatic text recognition with a focus on practical applications in concrete research scenarios and improving their automatic text recognition pipelines. Participants gained insights into the latest developments in OCR and HTR, focusing on open-source tools such as eScriptorium and workflows that facilitate the digitisation and analysis of historical and modern texts. Training covered not only the manipulation of pre-processing, segmentation, layout analysis, and post-processing, but also data management, empowering participants to achieve concrete goals in terms of the management, processing and reusability of their data within the duration of the summer school and beyond. The summer school was organised by DARIAH as part of the ATRIUM project, taking place from 1 September – 5 September 2025 in DARIAH Coordination Offices in Berlin. The organising committee included Anne Baillot (Instructor), Megan Black (ATRIUM Project Coordinator), Floriane Chiffoleau (Instructor), David Lassner (Instructor) and Toma Tasovac (ATRIUM Principal Investigator). ATRIUM is funded by the European Union under Grant Agreement n. 101132163. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.