The conventional wisdom is that the term wicca derives from the Indo-European root word of 'wic' & 'weik', meaning 'to bend or shape'. Another version of its origin is that it derives from an archaic/Old English word for wise.
The idea of primitive matriarchial religions was popular in Gardner's day, both among academics (e.g., Margaret Murray) and amateurs. But most academics now reject it on the basis of lack of evidence.
Wicca is part of a larger religious movement known as Neopaganism. Since its founding, various related traditions have grown up around Gardnerian Wicca, which is the term used for the specific beliefs and practices established by Gardner. However, not all of these groups consider themselves Wiccan, depending on how closely they adhere to those beliefs and practices.
Wiccans celebrate the four major Celtic seasonal festivals, Samhain, Beltane, Imbolc (or Imbolg or Oimelc) and Lammas (or Lughnasadh), as well as the solstices, Litha and Yule, and equinoxes, Ostara (or Eostar) and Mabon (see Wheel of the Year). They also hold Esbats, which are rituals held at the full moon.
Some Wiccans join groups called covens, though others work alone as so-called 'solitaries'. Some solitaries do, however, attend "gatherings" and other community events, but reserve their "circle work" (Sabbats, Esbats, spell-casting, worship, magickal work, etc.) for when they are alone.
Wiccans weddings can be called "bondings", "joinings", or "eclipses" but are most commonly called "handfastings". Some Wiccans observe an ancient Celtic practice of a trial marriage for a year and a day, contracted on Lammas (Lughnasadh).
Many Wiccans use special set of altar tools in their rituals; these can include a broom (besom), cauldron, Chalice (goblet), wand[?], Book of Shadows, altar cloth[?], athame (personal knife), altar knife, boline, candles, and/or incense. Representations of God and Goddess are often also used, which may be direct, representative, or abstract. Spargers[?] are sometimes also used.
The five elements: earth, air, water, fire, and spirit (akasha), are the elements of nature that symbolize different places, emotions, objects, and natural energies and forces. For instance, crystals and stones are objects of the element earth, and seashells are objects of the water element. Each of the four cardinal elements, air, fire, water and earth, are commonly assigned a direction and a color:
Elemental and directional correspondences may vary, however. It is common in the southern hemisphere, for instance, to associate the element fire with north (the direction of the equator) and earth with south (the direction of the nearest polar area.) Some Wiccan groups also modify the religious calendar to reflect local seasonal changes; for instance, in Australia Samhain might be celebrated on April 30th, and Beltane on October 31st to reflect the southern hemisphere's autumn and spring seasons.
There are many different traditions of Wicca. Major traditions include Gardnerian Wicca and Alexandrian Wicca[?], formed by important Wiccan thinkers Gerald Gardner and Alex Sanders[?]; Faery Wicca; and Dianic Wicca. A generally accepted and informative book describing the various "paths" within the pagan community is Margot Adler[?]'s Drawing Down the Moon : Witches, Druids, Goddess-Worshippers, and Other Pagans in America Today[?].
Wiccan morality is ruled according to the Wiccan Rede, which states "An it harm none, do what ye will." (The "an" is an archaic word meaning "if".) This very simplistic code leaves much up to the individual Wiccan, and that sense of personal reponsibility, rather than religious authority, is an innate part of Wicca. However, it may be construed as actually being far more restrictive on behavior than the "Golden Rule", in that it proscribes practicing anything that will result in any harm to anything.
There are two basic applications of the Wiccan Rede. One is the old construction which views the Rede as saying that what does not harm is acceptable, and all other actions are up to the individual to make the moral decision. The other is a modern reconstruction, adopted to deflect the unfounded criticism that Wicca has any relation to Satanism, that the Rede is a prohibition against causing harm.
Most Wiccans of the latter interpretation, however, realize that life on this planet survives by consuming other life, and so they modify the Rede (in practice if not in word) to "... harm none needlessly." This has applications beyond mere survival, as well; few Wiccans, for example, would have a problem harming a rapist in the act of his crime if that harm stops the crime.
Many Wiccans also promote the "Law of Threefold Return", or the idea that anything that someone does may be returned to them threefold. In other words, good deeds are magnified back to the doer, but so are ill deeds.
A summary of Wiccan views on homosexuality is on the Neopagan views of homosexuality page.
Though sometimes used interchangeably, "Wicca" and "Witchcraft" are not necessarily the same thing. The confusion comes, understandably, because both practitioners of Wicca and practitioners of Witchraft are called witches. In addition, many, but not all, Wiccans practice witchcraft and vice versa.
Wicca refers to the religion; the worship of the God & Goddess (or just Goddess), and the Sabbat and Esbat rituals.
Witchcraft, on the other hand, is considered a craft, and is sometimes called "The Craft". Witchcraft usually refers to the casting of spells and the practice of magick. Practicing witchcraft requires no belief in specific gods or goddesses and is much more like following recipes. There are "Christian Witches" and "Buddhist Witches" who practice witchcraft but who are not Wiccans.
The distinction between the two is, of course, not as black and white as this. There is a lot of crossover between Wicca and Witchcraft (for example: the mention of goddesses in spells, and the performance of spells during Sabbat rituals). However, the differences mentioned above are the general distinctions made between the two terms.
Some distinguish between high magick (ceremonial, ritualistic magick) and low magick (day-to-day, practical magick).
Some also distinguish between magick performed with coercion or unjust gain as its end, and term this practice the "left-hand path", and magick performed in accordance with the Wiccan Rede and general principles of not interfering with others unless the action has been requested by the others, termed the "right-hand path".
The history of Wicca is a much debated topic, and even many Wiccans are not sure of it. Generally, it is believed that Wicca is a modern invention in the style of old Pagan religions, following the thesis of Dr. Margaret Murray. There is good evidence, however, that while the ritual side of Wicca is undeniably styled after late Victorian occultism, the spiritual side is deeply inspired by the old pagan faiths, and this is why it is sometimes called "the Old Religion." Whatever rites Gardner had, if indeed he had any, were slim, and he expounded greatly with the works of Aleister Crowley. The main point is that while Wicca as we understand it is modern, both the practice of magick and the worship of the Mother Goddess and Great Horned God are ancient, and it would be fair to say Gardner merely took the idea and ran with it, though perhaps his claims that the religion was the "Old Religion" has hindered, rather than helped, Wicca gain widespread acceptance.