Teresa of Avila was a Spanish mystic and reformer born on March 28, 1515. She is best known for her role in the Carmelite Order, where she established the Discalced Carmelites, a reformed branch emphasizing a more contemplative and austere lifestyle. Teresa's writings on prayer and spirituality, including her famous work, "The Interior Castle," have had a lasting impact on Christian mysticism. In 1970, Teresa of Avila became the first woman to be declared a Doctor of the Church, recognizing her significant contributions to theology and spirituality. She was canonized in 1614, and her feast day is celebrated on October 15. Her legacy continues to inspire many in their spiritual journeys.