A glacial period (or alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The last glacial period ended about 15,000 years ago; The Holocene epoch is the current interglacial.
Quaternary ice age 
Glacial and interglacial
cycles as represented by atmospheric CO2
, measured from ice core samples going back 800,000 years. The stage names are part of the North American and the European Alpine subdivisions. The correlation between both subdivisions is tentative.
Within the Quaternary glaciation (2.58 Ma to present), there have been a number of glacials and interglacials.
In the British Isles the Pleistocene extent of the Quaternary ice age, has been subdivided into the following stages and superstages.
Last glacial period 
The last glacial period was the most recent glacial period within the current ice age, occurring in the Pleistocene epoch, which began about 110,000 years ago and ended about 12,500 years ago. The glaciations that occurred during this glacial period covered many areas of the Northern Hemisphere and have different names, depending on their geographic distributions: Wisconsin (in North America), Devensian (in Great Britain), Midlandian (in Ireland), Würm (in the Alps), Weichsel (in northern central Europe), and Llanquihue in Chile. The glacial advance reached its maximum extent about 18,000 BP. In Europe, the ice sheet reached northern Germany.
Next glacial period 
Since orbital variations are predictable, computer models that relate orbital variations to climate can predict future climate possibilities. Two caveats are necessary: that anthropogenic effects (global warming) are likely to exert a larger influence over the short term; and that the mechanism by which orbital forcing influences climate is not well understood. Work by Berger and Loutre suggests that the current warm climate may last another 50,000 years.
See also