Massive open online courses is an academic concept and educational technology phenomenon referring to large-scale online courses freely accessible to a global audience. As a research field, it investigates the pedagogical, technological, and social dimensions of delivering education at scale, exploring learner engagement, outcomes, platform design, accessibility, and the broader impact on traditional educational models. Characterized by potentially massive enrollment, open access, and fully online delivery, MOOCs are significant for their role in advancing research on scalable learning, global knowledge dissemination, and the evolving landscape of higher education.