This paper gives a review on the theory of bumps in coal mines at the Technical University of Munich, F.R.Germany. At first, the steep post-failure decrease of the material parameters is considered as the main characteristics of the material responsible for its pronencss to rock bursting. Then a simplified elasto-plastic theory, referred as an elementary theory in the text, is applied to the translatory bumps and some basic mechanisms of the bump are revealed. It is followed by a discussion on the effects o...