Ammonium is a positively charged ion, or cation, with the chemical formula NH4+. It is formed when ammonia (NH3) accepts a proton (H+). Ammonium is commonly found in nature, especially in soil and water, where it plays a crucial role in the nitrogen cycle, helping plants absorb nitrogen for growth. In addition to its natural occurrence, ammonium is used in various applications, including fertilizers, cleaning products, and food preservation. It is important in agriculture, as it provides an essential nutrient for crops. Ammonium compounds are also utilized in the production of explosives and pharmaceuticals.