Quintessence is a term that originally referred to the fifth element in ancient philosophy, alongside earth, water, air, and fire. It was believed to be a pure, celestial substance that made up the heavenly bodies and was thought to be the essence of all matter. In modern science, quintessence describes a hypothetical form of dark energy that could explain the accelerated expansion of the universe. In cosmology, quintessence is considered a dynamic field that changes over time, unlike the cosmological constant, which remains constant. Researchers study quintessence to better understand the universe's fate and the nature of dark energy, which constitutes about 68% of the universe's total energy density.