The IWOTA 2023 conference proceedings will be published in the book series Operator Theory: Advances and Applications by Springer/Birkhäuser and edited by Joe Ball, Hans-Olav Tylli, and Jani Virtanen. In addition to original research articles, we welcome broad survey articles on current developments in the field. All submissions will be reviewed and strict standards of refereeing will apply. The deadline for contributions is February 15, 2024, via iwota2023@helsinki.fi.