Citizen science is a collaborative approach that involves the general public in the development and dissemination of knowledge. In the twenty-first century, citizen science has experienced a huge expansion in activity, leading to different understandings, approaches, classifications, and taxonomies. While postdigital citizen science eludes conclusive definition, its main challenge consists of three aspects the technological, the political, and the participatory. In the third decade of the twenty-first century, postdigital citizen science is expanding into postdigital citizen social science and, postdigital citizen humanities, and asks important questions about who is a postdigital citizen and what postdigital research is.