The Shield Knot is a protective old Celtic symbol. This knot was used to fend off bad spirits and other dangers by placing it near sick people or on battle shields. It can be fashioned in a variety of styles, but its distinguishing feature is its four different corners. Shield Knots are frequently square-shaped or look to be squares within circles. The Shield Knot, in addition to being a part of ancient Celtic culture, is thought to have been employed by various other cultures for invoking the protective power of the Gods who represent the land.