This article examines the significance of emotion for the processes of teaching, studying and learning. The goal is to demonstrate on the basis of both theoretical examination and empirical data that emotional processes are crucial for human learning and should be taken into account in online teaching and learning as well. Emotional factors during studying influence in several ways whether one studies, how one studies, whether one learns and whether one remembers what one studied. We also examine online group dynamics in online teaching and studying from the point of view of shared emotional states and online conveyance of emotions. Emotional situations related to studying are also examined from the point of view of cognitive and emotional load and via the concepts of situational anxiety and situational pleasure. The examples in the empirical data were collected during 2005-2006 from online courses of the Cornet project. The data was analyzed by classifying the data referring to emotionality with nVivo program under special themes described in this article. The data contain student essays "I as a learner" during the "Education, organisations and culture" study unit (N = 12) and students' study-related email messages during the "Learning organisation and small group dynamics" study unit (N =28).