Humanoid robot operation requires balancing to prevent failures, such as fall over. This is a crucial task in legged robots and thus several researchers are working on this topic. Fall prediction, controlled fall, and fall recovery become important topics in understanding robot control and allow legged robots to function in challenging real-world environments. This paper aims at setting up methodically the problem definition of humanoid falling and further identifying and surveying working techniques in the literature. The focus is to categorize all methods that were used in the community, identify the solved and open questions, as well as propose directions of research in the field. The paper is based on experimental research that has been done on a full-size humanoid robot.