In the symbolism of the four classical elements, fire is a purifying, masculine energy, associated with the South, and connected to strong will and energy. Fire destroys, and yet it also can create new life.
In some traditions of Wicca, this triangle is the mark of a degree of initiation. It is sometimes displayed within a circle, or Fire may be represented by a circle alone. The triangle, with its pyramid shape, is often symbolic of the masculine aspect of the Divine. In 1887, Lydia Bell wrote in The Path that, "...the triangle is our symbol for truth. As a symbol for the whole of truth, it holds the key to all science, to all wisdom, and its study leads with certain steps to and through that door wherein the mystery of life ceases to be a problem and becomes revelation... The triangle is a unit, each part of the triangle is a unit, hence, it follows that every part manifests the whole."
In Elements of Witchcraft, Ellen Dugan suggests a focused fire meditation as a way of harnessing this volatile element. She associates fire with transformation and change. If you're looking at a working related to some sort of inner change and growth, consider doing some colour-oriented candle magic. If you have access to any sort of flame -- a candle, bonfire, etc. -- you can use fire scrying for divination purposes.
In some Pagan traditions, Beltane is celebrated with a Bale Fire. This tradition has its roots in early Ireland. According to legend, each year at Beltane, the tribal leaders would send a representative to the hill of Uisneach, where a great bonfire was lit. These representatives would each light a torch, and carry it back to their home villages.
Fire has been important to mankind since the beginning of time. It was not only a method of cooking one’s food, but it could mean the difference between life and death on a frigid winter night. To keep a fire burning in the hearth was to ensure that one’s family might survive another day. Fire is typically seen as a bit of a magical paradox because, in addition to its role as destroyer, it can also create and regenerate. The ability to control fire - to not only harness it but use it to suit our own needs - is one of the things that separates humans from animals. However, according to ancient myths, this has not always been the case.
Article: Wigington, Patti. "Magical Pagan and Wiccan Symbols." Learn Religions