If this is your mental image of a Witch you need educating...read on.

This is a stereotype portrayed in films and cartoons intended to prejudice the truth behind Witchcraft.
Witches do have besoms (brooms) and sometimes wear cloaks (when it's too cold to be sky-clad during rituals). The pointy hat is mythical, as is physical flight, however, the 'old hag' physique is not a prerequisite. :-^)
Witchcraft is a religion just like any other, and is one of the fastest growing religions in the world.
So what is a Witch and what do we do? For starters, the term Witch has absolutely nothing to do with Satanism. Witchcraft is an Earth based religion, meaning that it is based upon reverence for nature, respect of animals, and a respect of our environment and those in it. Witches practice folk magick, especially magick involving herbs, stones, colours, water and the energy of nature. However, we do not perform animal sacrifices; the only sacrifices made are of a spiritual nature. Witches can be both male and female; phrases such as wizard and warlock are not normally used, in fact warlock means 'oath breaker'! Many Witches term themselves as Wiccans, and the two are usually seen as synonymous, although some may disagree. Wiccan purists will state that Wicca does not teach spell-casting or candle magic...
Wicca/Witchcraft is a polytheistic religion, this means there is more than one figurehead, a Goddess of whom has many names (see Goddesses), and a God whom also goes by many names (see Gods). By contrast, monotheistic religions believe in only one figurehead, for example, Christianity. Witches practice ritual observance of lunar events (see Pagan calendar), the seasons and their effect on agriculture. The rituals are split into two groups, Sabbats and Esbats. There are eight Sabbats in a year representing the cycle of birth and death of the God, these being Yule, Imbolc, Ostara, Beltane, Litha/Midsummer, Lughnasadh, Mabon and Samhain. Esbats on the other hand are full-moon rituals, and there are usually thirteen of these in a year. All of these rituals are performed within sacred or magick circles, and are used for the purposes of asking for guidance and giving thanks to the Goddess and God, and are often used for the performance of magick.
Most Witches are members of a coven, in which there will be a High Priestess and a High Priest. The other members (usually 11) will be Witches of varying degrees of aptitude/initiation. Coven rituals and magick can me far more powerful, as like most other things in life groups evoke far greater strength than one person acting alone. Solitary Witches are also commonplace, either through choice or because sometimes it can be difficult to find a coven with openings (they don't advertise in national newspapers nor do they proselytise their religion by door-to-door sales tactics!).
Wiccans conform to a moral code called the Wiccan Rede, it simply states 'An it harm none, do what thou will'. This means that as long as you do no harm to anyone or anything, including yourself, you may do anything that your heart desires and has the willpower to accomplish. It is rare that you will find a Witch that performs magick for the purposes of harm, as ultimately they will be harming themselves. This comes about by the 'Threefold Law' that states that anything that you do will be returned to you three times stronger. So if you perform good it will be returned to you threefold, likewise any evil will be returned to you threefold - so it makes sense to only do good.
There are many differing branches of Witchcraft, encompassing variations of ritual practice and terminology, however we all fall under the same generalised beliefs above. Witchcraft has been shrouded in secrecy for many years, many people fearing persecution for their natural beliefs. Much of the information on this site would have been very closely guarded until a few years ago, being only for the eyes of the initiate. But with the rapid growth in our religion, and with more and more books being published on the subject, we are all able to share in the ancient knowledge and benefit from its wisdom, hopefully without fear of reprisal. Despite all this, information that is more complex and in-depth has not been revealed, nor is it likely to be, as one of the oaths of Wicca is to keep practices secret.