The representations of the trinity knot vary by personal beliefs and religion, but for many it represents the Father, the Son and the Holy Spirit. The trinity knot is also referred to as the Triquetra, which means triangle.
In paganism it is believed that the trinity knot stands for the natural forces including earth, air, fire and water. On a more spiritual level in the pagan religion, it symbolizes life, death and rebirth. No one knows for sure who created the trinity knot, but this has been some controversy for years. Christians believe the symbol started with the Monks, but many believe that the knotwork symbol was originally Celtic.