A talik is a patch of unfrozen groun in an area of permafrost. In areas of continuous permafrost it often occurs underneath shallow lakes (thermokarst lakes). It does not freeze during the winter and is thus not merely part of the active layer of the permafrost. Sometimes open, closed and through talik are distinguished. These terms refer to whether the talik is completely surrounded by permafrost, is open to the top or open to both top and unfrozen layers beneath the permafrost, respectively.