Some practitioners, upon dedicating themselves to the Craft, choose to take on a new name to symbolize their rebirth or transformation into a new life. These names are called Magickal Names or Coven Names. Although it is not necessary to take on a magickal name, it can be a useful tool for some as it is yet another way to tune in to the magickal side of their nature, and helps them get into the proper frame of mind to commune with the Divine and to perform rituals and spells.
        The practice of taking on magickal or coven names allegedly began during the Burning Times when a practitioner's very life could depend upon others being unable to name and identify them as a witch. If the coven members knew them only by their coven name, they felt more protected as those people could not reveal the practitioner's true identity, other than by physical description, even under torture.
        More validly, it is an ancient belief in many cultures that to know a person or spirit's name gives one power over that person or that spirit. That is why some practitioner's have more than one magickal name. They have a public Craft name for use among other practitioners, a coven name given to them at their initiation into the coven and known only to coven members, and a secret name known only to the practitioner and possibly their god(s).
        Magickal names are arrived at in a variety of ways. Some practitioners choose to adopt the name of a deity they feel affinity for and wish to honor (most commonly, these names are altered into whatever in that language would mean "son/daughter of [insert deity name here]"), while some practitioners find or are "given" their magickal name through dreams, vision quests, trances, etc. Others follow elaborate formulas having to do with numerology, their birth number, the sign or element under which they were born, or use divination tools such as Tarot cards and runes, using those numerical values and phonetic correspondences to lead them to their new name. Other practitioners choose the name of a plant, stone, color, element, and/or their totem animal(s), which they identify with. Still others keep the name given to them at birth and never choose a magickal name at all. It is a totally individual decision. But, if you do decide to choose a magickal name, take into consideration that choosing the name of an element, animal, plant, stone, color, deity, etc., will draw those specific energies to you, and that some deities may not appreciate having their names taken without their consent.
        The magickal name you choose should reflect your truest inner self. Therefore, a lot of thought should be put into the process. Some practitioners take as long as two years or more to find the correct name for themselves. It is an important decision and should not be rushed. The right name will come to you at the right time, and you will know beyond a shadow of a doubt that it belongs to you.
        Also, some practitioners change their magickal name many times during their lifetime to mark different phases in their life. As we grow and learn in our chosen path, we change. Sometimes the magickal name we have chosen no longer describes the individual we have become. At that point, we may choose to take on a new magickal name to reflect these changes, or add to the original name in some way.
        The following is a list of books and a couple of websites that may help you in your search for the perfect magickal name:

"The Complete Book of Magickal Names" by Phoenix McFarland
"The Magical Name" by Ted Andrews
"The Sacred Power in Your Name" by Ted Andrews
"Rites of Passage, the Pagan Wheel of Life" by Pauline Campanelli

Numerological Formula For Choosing Magickal Names:
At the bottom of this page, there is also a set of links for examples of names with specific birth numbers.

Table of Correspondences
This table shows you which elements, directions, some animals, some plants, colors, etc., that correspond with each other that might help one choose an appropriate magickal name.