These proceedings contain the papers of the 18th International Conference on Cognition and Exploratory Learning in the Digital Age (CELDA 2021), held virtually, due to an exceptional situation caused by the COVID-19 pandemic, from October 13-15, 2021, and organized by the International Association for Development of the Information Society (IADIS). The CELDA conference aims to address the main issues concerned with evolving learning processes and supporting pedagogies and applications in the digital age. There have been advances in both cognitive psychology and computing that have affected the educational arena. The convergence of these two disciplines is increasing at a fast pace and affecting academia and professional practice in many ways. The CELDA 2021 Conference received 68 submissions from more than 21 countries. Out of the papers submitted, 34 were accepted as full papers for an acceptance rate of 50%; 16 were accepted as short papers, and 2 were accepted as reflection papers. In addition to the presentation of full, short and reflection papers, the conference also includes one keynote presentation from an internationally distinguished researcher: Dr. David Scaradozzi, Department of Information Engineering, Università Politecnica delle Marche, Italy. [Individual papers are indexed in ERIC.]