Wicca is a nature-based Pagan religion founded in England in the late 1800's by Gerald Brousseau Gardner who called it "The Craft of the Wise". It wasn't until the 1940's that the initial books were written that brought Wicca into the public eye and wasn't referred to as Wicca until the 1960's. The traditions and rituals were built on ancient Paganism and a collection of metaphysical and paranormal activities and beliefs. It is the fastest growing religion in North America, but also highly misunderstood.
Wicca was originally known as witchcraft, but was changed to rid us of the stigma that came with being a witch, through history and even in literature of today. With that said, not all Wiccans are witches and not all witches are Wiccan.
For those who are Witch, you can practice on your own, or as part of a Coven. A Coven is typically ran by a High Priest and/or High Priestess who would be the most experienced of the group and typically strive to hold a total of 13 Witches total. Just be aware that Covens are not usually easy to come by and just because you find one, does not mean it will be the right fit for you or that you will be a good fit for them. The majority of witch's these days tend to practice on their own for these reasons.
Wicca focuses on the powers and energies of nature and the elements and how they can connect us to our higher self and the Devine. Traditionally, Wiccans work with the Triple Goddess and the Horned God as their main Deities, but many work with a number of others depending on their needs and goals. Just as, many Wiccans don't work with any Deities at all.
The Wiccan religion does not believe in heaven or hell, but in a spirit realm. Your spirit from this life goes to the spirit realm, but your soul gets reincarnated to new life. Some Wiccans believe that reincarnation takes time and that your soul goes to "The Summerland" for a period of time first to rest, while others do not believe in reincarnation at all.
The Wiccan Rede is the key moral statement followed by Wiccans. "An ye harm none, do what ye will." Which translates to; do as you will as long as you are not hurting anyone (people, animals or nature). All living things carry memories and knowledge and should be respected. This means, contrary to popular belief, we do not worship Satan or hold sacrifices.
Some Wiccans follow a second rule called The rule of three or the threefold law. The rule of three means, whatever energy you put out into the universe, gets returned to you threefold. This means positive or negative. Some view this rule as karma (meaning not necessarily returned three times over), or I have also heard others mention a sevenfold law. The main goal for most Wiccans is balance of light and dark.
Wiccan holidays follow the Wheel of the year. This includes four major Sabbats and four minor. The major Sabbats are celebrated by most Wiccans and are; Samhain/ All Hallow's Eve (Oct. 31 or Nov. 1), Imbolc/ Candlemas (Feb. 1 or 2), Beltane/ May Eve (April 30 or May 1) and Lammas/ Lughnasadh (Aug. 1). The minor Sabbats follow the equinox's and solstices and are not always celebrated as widely. The minor Sabbats are; Yule/ Winter Solstice (Dec. 20-23), Ostara/ Spring Equinox (March 20-23), Litha/ Summer Solstice (June 20-23) and Mabon/ Fall Equinox (Sept. 20-23). These dates are for anyone in the Northern Hemisphere. In the Southern Hemisphere they are forwarded 6 months in order to coincide with the proper seasons. A lot of Wiccans will also celebrate Esbats, which follow the cycles of the moon. Each holiday has many different rituals and activities that can be done to commemorate the turning of the wheel and the change in seasons and nature. Find what works with your life and schedule to make your own traditions.
Hope this helps for anyone looking to become part of Wicca or just to learn about it, without overwhelming you too much!