Sweeteners are substances used to substitute sugar for providing sweetness, including natural sweeteners like stevia and synthetic ones like aspartame. They have diverse structures, but their common goal is to deliver sweetness without adding extra calories. Sweeteners do not directly participate in biological reactions within cells or tissues but stimulate taste receptors to produce a sensation of sweetness. Perception of sweetness may vary across different tissues and cell types, depending on the expression of taste receptors. The safety and health impacts of sweeteners remain a focal point of research and discussion, especially concerning their potential long-term effects on metabolic pathways.