This is often the first question visitors to this site will ask, and perhaps the most common when conversing in day to day life. I feel, and have always felt, that this is to a degree a personal thing, a personal path, so I will include a more abstract view, my own thoughts and the history of this term.
Wicca as we know it today is an amalgamation of practices both ancient and new, brought together under one name in public view by Gerald Gardner (1884 - 1964), the man commonly named as the father of Wicca. Practices from various other paths including the Free Masons and ceremonial magic were drawn upon and added to the rituals of a New Forest coven he was initiated into in 1939, creating what became known as the Gardnerian tradition of Wicca. Gardner was determined to grow this religion, writing about it and after the Witchcraft Act of 1736 was repealed in 1951 gaining media attention. He had formed the Bricket Wood coven into which Doreen Valiente and other notable members were initiated, Doreen going on to become High Priestess and assist with the penning of many works before splitting from the coven. From there the tradition spread throughout the late 50s and 60s, continuing to grow slowly but surely until the advent of the internet allowed the information to spread and flourish further. Today many follow one of the various traditions of Wicca or their own path with it's teachings and practices at the core. Practitioners celebrate both as a part of a coven or alone, bringing aspects of it into day to day life in ways both big and small. People from all walks of life are drawn to the faith, following the tenant "An it harm none do what ye will".
In Personal Terms
For me, while you can describe Wicca in technical terms and history, this does not accurately convey what it means, any more than to flatly describe Christianity can share what it means to those who follow that path. Wicca is a celebration of nature and the magic of life which surrounds us all, it's the whispers of the wind in the trees, the fire of Autumn leaves shining brightest in their last days and the slumber of an ancient oak in the depths of winter. All those moments which take our breath away, the reflective sunrises and the nights under moonlight that fill our souls with song, we celebrate and revere. Even in our darkest moments that connection is there waiting to be found, helping us to embrace the shadows and understand that light and shadow need each other to bring balance. Each person brings to the practices something new, a change to a chant, a new method, or just their own light, forming threads that weave together into a vibrant tapestry that can bring joy to those within.
Are Wiccans Witches?
Not all Wiccans practice magic and not all Witches follow Wicca. You can by all means be both and many Wiccans do work ritual magic and spells as part of their practice. An important thing to remember is Witch is a very broad term, practice can vary hugely from place to place and person to person with practices originating in modern times or the distant past. The stereotype green hag, cackling child eater is a media myth. Wiccans believe (as do many other paths) that what is sent out into the world returns threefold, in essence karma, so hexing and such is not undertaken by those of us who also practice Witchcraft. Any magic should be done with thought, care and clear intent to avoid inadvertent harm.
Wiccans Do Not