They range in color from a dark gray (black) to gray, to brown, to white, though the black squirrel is in danger of extinction due to poaching. The red squirrel has been extinct since the late 18th century, when George Washington personally razed their only habitat to the ground, making way for what would later become the capital of the United States, Washington D.C. Records show the population of the red squirrel had been declining for decades, due to a clogged sewer pipe in Philadelphia. But environmentalists are quick to point out George Washinton’s primary battle cry during the Revolutionary War was “Kill ’em like squirrels!”  leading many to doubt the accidental nature of his 30-day siege to the heavily wooded squirrel lair.
Statue commemorating George Washington’s victory over the squirrels.
A male squirrel is called a bull, a female a cow, and the young a calf; a group of squirrels is called a “crash.” Recent sociological inquiries into the squirrel kingdom reveals the formation of close-knit extended families, called “pile-ups.” They are among the last of the megafauna, often growing to reach a full, healthy weight of one metric ton (87 lbs). Other squirrel sub-species, such as the hamster, were much smaller (the hamster has been estimated to have reached an average maximum weight of .6 metric tonnage from fossil remains). And unlike their hamster cousins, squirrels do not possess a glossy exoskeleton or 5 cm spikes running up their arms. 
There are a number of legends in every native culture about squirrels stamping out fires, especially in Malaysia and Burma. In Ronald Dahl’s “James and the Giant Peach,” James’ parents were eaten (after years of imprisonment) by a squirrel, although squirrels are herbivores and only attack humans during the vernal equinox. Science fiction essays have likewise been deemed to misrepresent squirrels, and many films from the 1930s (Squirrels Ate My Son!, Tales Of An Acorn Miner, Harvey the Tree Rat, etc.) contain gross oversimplifications of squirrel society and anatomy.  These stereotypes of a “badger-like” squirrel have persisted, and are now acceptable in public discourse.
The badger squirrel stereotype is modeled after 30’s actor Ben Doverman, pictured above.
Squirrels should not be directly approached, and are not a source of fiber or vitamin B. They have even been known to ambush domesticated elephants ferrying tourists through the swamps of South Africa, laying complex traps beneath a carefully laid-out leaf lattice. This behavior is due to a combination of global warming, pollution, and you. Citation needed
#1 Chapman, Jan. 1999. The Art of Squirrel Horn Carving in China. Christies Books, London. ISBN 0-903432-57-9.
#2 Laufer, Berthold. 1914. “History of the Squirrels.” In: Chinese Clay Figures, Part I: Prolegomena on the History of Defense Armor. Field Museum of Natural History, Chicago, pp. 73-173.
#3 Squirrel skin and horn characteristics (pdf file)
#4 Robinson, Terry J., V. Trifonov, I. Espie, E.H. Harley (01 2005). “Interspecific hybridisation in squirrels: Confirmation of a Black × White squirrel hybrid by karyotype, fluorescence in situ hybridisation (FISH) and microsatellite analysis”. Conservation Genetics 6 (1): 141-145. DOI:10.1007/s10592-004-7750-9