An object having the shape and often the appearance of an erect penis, used in sexual stimulation.
American Heritage Dictionary, Fourth Edition, 2000.
History
For thousands of years, dildos have played a role in erotic culture. Although Upper Paleolithic art has led to speculation that the first models were made of dried camel dung covered with resin, the first documentation of a dildo comes from Ancient Greece. The city of Miletus was renowned for its leather, wood, and ivory olisbos - they were sold not only in the shops of the city, but by Miletan traders on Mediterranean circuits. Paintings on Greek vases from the fifth and fourth centuries BCE depict dildos, and a third-century BCE play features two women discussing the superior craftsmanship of dildos from Miletus. They may also have been used in deflowering ceremonies, wherein a dildo was attached to a statue of Priapus and used to prepare a young woman for marriage.
In medieval times, a plant called Cantonese groin was soaked in hot water to enlarge and harden it for use as a dildo, and in Renaissance Italy leather and wood versions required olive oil to make them sufficiently lubricated for use. Although the exact etymology of the word "dildo" is unknown (it is sometimes claimed to be from the Latin for "open wide"), it is most commonly supposed that the term comes from the Italian word diletto - to delight; "dildo" first appeared in English usage around the 1500s.
Outside Europe, dildos had also been in use since ancient times. In China, they were sometimes made of wood, jade, and ivory; there are reports that unripened bananas were used in Arab and Polynesian countries. The Kama Sutra refers to dildos made of wood and tubular stalks or reeds tied to the waist, and a Chinese painting from the nineteenth century depicts a woman using a dildo attached to her shoe.
The modern history of dildos begins with their use in medicine. In the mid-1800s, women were treated for what was known as hysteria, which doctors of the time believed could only affect females. Physicians would sometimes "treat" a patient by massaging her clitoris, and occasionally dispensed a phallic object for her use - calling it a therapeutic device, though a more colloquial term of the day was "widow's comforter." It was also around this time that dildos were first fabricated from rubber. In the early twentieth century, dildos appeared not only in early erotic cinema but also in magazines and catalogs marketed for women. Even the renowned Sears-Roebuck catalog carried them, calling them "a device for anxiety and female tension." They were promoted as something to keep women relaxed and content, but by the 1940s their sexual overtones had been recognized and they were no longer popular. In 1966, the first one-piece, battery-powered, vibrating dildo was patented, but during the 1970s many cheap dildos were produced. In the late 1980s and early 1990s, sex-positive boutiques appeared and began selling higher-quality merchandise made of various polymers and silicone.
Varieties
There are almost as many types of dildos as there are people who use them. They are made in a wide variety of sizes, shapes, colors, and materials, and for many different purposes. Perhaps the most popular material is silicone, which is non-porous and therefore easily cleaned, making it the safest type of dildo. Silicone dildos also hold warmth well, but they are not as flexible as jelly dildos and usually cost quite a bit more; acrylic and Cyberskin dildos tend to be expensive. Some specialty dildos are made of metal, glass, and other unusual materials. Jelly dildos are commonly just one color, but those made of other materials can be dyed several colors, including multicolor swirls. Flesh-toned dildos (typically of Caucasian or African coloring) are often available, both in realistic and less exact dildos. There is a wide range of realism possible as well: while virtually all dildos are phallic in shape, some are pure shafts (these are the best for use with a harness) while others add balls, ridges, and a head. Some dildos have curves or waves to them - a few models are "flexible" thanks to a wire inside - while others look remarkably like a dick and claim to be molded from the actual penis of an actual porn star. Japanese dildos are among the most unique in shape because of that country's prohibition on sex toys that look like body parts. Animals are a common substitute, with dolphins and beavers among the more popular shapes; some Japanese products look almost exactly like a penis-shaped dildo but contain subtle tricks, such as a face just under the head to make the dildo a "woman." Some dildos are created for specific purposes or just to be terribly unique. These include the barbell-shaped Kegelcisor, the S-shaped clear acrylic Crystal Wand, the Celtic Phallus, a hard polyurethane resin dildo carved with intricate patterns, the Pack and Play, designed to be used for packing and penetration, and the clear acrylic Observer - optically engineered so the rounded end becomes a "view port."
Care
Any dildo of any type should be cleaned after every use, even if a condom was used the entire time. Silicone dildos are easily cleaned in the dishwasher or by spending some time in a pot of boiling water - this is not possible for dildos of other materials because they are often more porous or would break down. Some adult-oriented companies make special cleansers for toys, but a little soap and water or rubbing alcohol works as well. Cyberskin dildos should be stored in a box with some talc on them.
Controversy
Laws against dildos have been on the books in a few Southern states - including Georgia and Tennessee - for years. One was enacted very recently in Alabama, surrounded by much controversy over its legality. The law stated "the sale, production or distribution of... any device designed or marketed as useful primarily for the stimulation of the human genital organs" was punishable by one year in jail or hard labor, and a $10,000 fine. A few months later, in August 1999, a federal judge declared the law unconstitutional, saying that it bore no "rational relation to a legitimate state interest" and interfered with the potential therapeutic health benefits associated with sex toys. The Office of the Attorney General of Alabama appealed the decision to the 11th Circuit Court of Appeals, who, in October 1999, declared that Alabama's anti-obscenity law was "rationally related to the state's legitimate government interest in public morality." The law remains on Alabama's books today, and apparently legislators in that state, Georgia, and Tennessee haven't considered that dildo fans may revert to cucumbers for their sexual pleasure.
Sources
http://www.sexscrolls.com/article1013.html
http://www.jackinworld.com/library/articles/history.html
http://www.sextoyguides.com/attitudes/history.asp
http://www.xandria.com/learn/history/index.shtml
http://www.datingfun.com/sex/techniques/sex-history.asp
http://www.babeland.com/catalog/dildo_history.html
http://www.blowfish.com/catalog/guides/dildos.html
http://www.atheists.org/flash.line/dildo2.htm
http://sexuality.about.com/library/weekly/aa030199.htm
http://sexuality.about.com/library/weekly/aa051099.htm
http://www.eroticguide.com/toys/toys/dildos.htm (Google cache version)
http://www.inetgoods.com/sextrivia/Dildo%20History.htm (Google cache version)
If my descriptions and information seem limited, this is because I have tried to stick to the topic at hand. Although I could have delved into buttplugs, vibrators, strap-ons, and several other subjects, I have tried to keep this writeup exclusively about dildos and refer the reader to other nodes for more information.