Glacier storage is a widely used term, applied to different processes and time-scales by different disciplines in hydrology and glaciology. We identify that storage occurs as ice, snow, and water associated with three time-scales. Long-term storage concerns storage of ice and firn as glaciers on time-scales of years to centuries and longer. This storage affects global sea level and long-term water balance of glacierized catchments and is especially important for water resources in arid and semiarid areas. Intermediate-term storage is applicable to processes such as storage and release of snow and water, in and on a glacier on a seasonal scale. This is also the most common definition in the literature implied by the term storage. Intermediate-term storage affects runoff characteristics in glacierized catchments and downstream river flow regimes. Short-term storage concerns diurnal effects of drainage through the glacier including routing through snow, firn and en- and subglacial pathways. In addition to these time-scale dependent processes there are also event-driven storage releases, termed singular storage releases, including drainage from glacier surges and drainage of glacier-dammed water. These events are associated with glaciers but do not exhibit cyclic response or have irregular occurrences. It is evident that glacier storage is not handled well by current conceptual or mathematical models and that, e.g. sub- and englacial storage are poorly constrained. Hence, holistic approaches to studying and modelling glacier storage are of major importance to fully integrate glaciers into the hydrological balance to be used for water resources and river flow predictions on all time-scales.