The term "biogeobattery" describes a natural phenomenon in which biotic processes generate electrical currents within the surface of the earth. The biogeobattery phenomenon is caused by microbes driving electrons flow that is coupled to spatially separated biogeochemical processes. The biogeobattery phenomenon does not occur everywhere that microbially mediated redox interfaces occur because it requires specific geochemical and microbiological conditions. The phenomenon is much more apt to occur when a redox interface occurs at contaminated sites that are rich in organic material that is being biodegraded. The biogeobattery phenomenon was first identified when it was proposed to explain strong self-potential anomalies, which were believed to be associated with microbe-driven redox reactions, at the Entressen landfill in southern France. Subsequent laboratory experiments and field studies have provided evidence for the biogeobattery phenomenon. For instance, the biogeobattery phenomenon has been found in marine sediment, in which electrons generated by microbes (metabolizing sulfide) in anoxic zones were transferred over "long distances" to oxic zones where they were taken up by oxygen. Knowledge of the mechanisms involved in electron transfer is fundamental to understanding this natural phenomenon. A great deal of time and energy has therefore been put into identifying these mechanisms. However, the mechanisms involved in long distance electron transfer in the natural environment have not yet been determined. One possible mechanism involves long filamentous bacteria from the Desulfobulbaceae family, which were found to function as electrical cables, transporting electrons across centimeter-scale distances, in a marine-sediment-based biogeobattery. Electrochemically active species, such as conductive minerals and microbial nanowires, are also potential mediators for the long distance transfer of electrons in natural environments. The biogeobattery theory presents novel viewpoints in the field of microbial ecology that are different from some viewpoints that have been held for a long time. These novel viewpoints could have very significant effects on our understanding of the ways in which the geochemical cycles of elements such as C, N, and S are driven by microorganisms in the earth's surface. The biogeobattery theory also provides new knowledge of the mechanisms involved in electron transport in subsurface environments. The biogeobattery phenomenon could have important effects on many vital biogeochemical processes, such as the anaerobic mineralization of organic matter, greenhouse gas emissions, and the degradation of contaminants. There can be no doubt that the biogeobattery phenomenon is becoming an important topic at the forefront of research in the earth science, microbiology, and ecology fields. A wide range of knowledge, including of geophysical, geochemical, and microbiological models and methods, needs to be combined to understand the biogeobattery concept. However, so far only a few technologies have been used to study the theory and effect of biogeobattery. Micro-targeting electrodes can be regarded as the most important and mature of these technologies. Low-frequency geoelectrical methods, such as self-potential, resistivity, and acoustic techniques, which provide geochemical signature data that are complementary to each other and to in situ measurements, may also be developed into powerful tools for the use of the biogeobattery phenomenon. In this review, we will redefine the concept and scope of the biogeobattery phenomenon to reflect recent research. In particular, we will summarize the regions where the biogeobattery effect occurs and the conditions under which the biogeobattery effect can take place. Some methods that may be useful for studying the battery potential, the response relationship between the anode and cathode, the conductive medium, and other parameters, will be introduced in detail. The ecological implications and future research needs will be discussed.