Continential glaciers today, in addition to Greenland and Antarctica, can also be found in places such as Iceland, and Baffin Island. The key thing about continential glaciers is that, unlike alpine glaciers, they do not conform to local topography, but rather bury it. They flow outwards from a center, the highest ice elevation, and the maximum thickness of the ice.
Alpine Glaciers, of course, are found in the major mountain ranges of the world. The Himalayan Mountains, Rocky Mountains, the Alps (of course!) and the Cascades all have a variety of glaciers. Small mountain ranges, such as the appalachians, are too short or poorly situated for glacier formation.
Glaciers today, all together, compose about 10% of the land area of the Earth's surface. The map to the left shows, in white, where glaciers can be found today. 10% may not sound like a lot, but from all the white, you can see it is a huge amount of ice. About 75% of the Earth's freshwater resides in the glaciers. Perhaps, one day, should population pressures cause water shortages, drinking glacier water will not be limited to places which indirectly use meltwater from Glaciers, like the Pacific Northwest.
During the most recent Ice Age, which began 1.5 million years ago, and may not have actually ended, the glaciers extended three times their size, to cover nearly a third of the land area of the Earth's land surface, as you can see from this diagram. One thing to note from the diagram, too, is the sea level consideration. During the Ice Ages, since so much of the planet's water is locked up in these ice sheets, sea level is lower than it is today. Thus, that nice beachfront property you have on Long Island, today, was far inland 18,000 years ago.
Such a drop in sea level at this time also allowed for travel between Siberia and Alaska, allowing humans to enter our continent for the first time, and after the ice ages ended, to await "discovery" by Christopher Columbus and his ilk.
