The Elven Star, or seven-pointed star, is found in some branches of the Faerie tradition of Wicca. However, it has different names and can be associated with many other magical traditions.
According to The Element Encyclopedia of Secret Signs and Symbols, the Elven Star (or Faerie Star) is also representative of the seven stars called the Pleiades. It is also a reminder that seven is a sacred number in many magical traditions -- it is connected with the seven days of the week, the seven pillars of wisdom, and many other magical theories. In Kabbalah, seven is connected to the sphere of victory. Aleister Crowley used a septagram as the emblem of his Order of the Silver Star.
In modern Pagan practice, this symbol can be used to keep information hidden from the prying eyes of the outside world. Use it on your Book of Shadows, to keep the contents safe, or on an amulent to prevent others from reading your thoughts.