Meltwater is the term for any water that occurs as a result of melting snow or ice. It is primarily used to describe glacial melting and the long-term results of this slow process.
Meltwater typically occurs on glacial surfaces due to solar radiation, although other factors, such as hot bedrock beneath the earth's crust and friction, may cause glaciers to melt. Generally, at ideal points during the day, meltwater becomes so prevalent that it does not immediately refreeze to the glacier. Instead, it meanders along the ice's surface, creating small valleys which can help induce further melting.
Ocassionally, meltwater will occur inside the glacier due to pressure and cause englacial drainage - small spaces of air within the glacier that flow like rivers, complete with branches and large reservoirs. Perhaps the least common (but most dangerous) form of meltwater draining is subglacial draining. This occurs when water at the bottom of the glacier is heated by the earth's convection or the high pressures of the glacier's weight and melts. This drainage can sometimes create a "water slide" on which the glacier can surge forward - sometimes resulting in an avalanche or earthquake. However, this is rarely seen in nature.
Over time, meltwater deposits will eventually form intricate stream channels and rivers within glaciers. Visiting the frozen coasts of Canada and Alaska will reveal large bodies of water encircled by ice - the result of the tiniest drops of water. And about a million years or so ...