The document discusses virtual reality, augmented reality, and mixed reality. It defines each term and provides examples of applications. Virtual reality immerses users in a digital environment, while augmented reality layers digital content on the physical world through devices like phones. Mixed reality combines aspects of virtual and augmented reality by allowing digital objects to be viewed regardless of location. The document outlines examples of educational applications of these technologies and projects involving augmented reality that have been developed in Bragança, Portugal.