The chemical symbol for potassium is K. This symbol is derived from the Latin name for potassium, which is "kalium." Potassium is a vital mineral and an essential nutrient for both plants and animals. It plays a key role in various biological functions, including regulating blood pressure and fluid balance, as well as muscle contractions and nerve signaling. It is commonly found in foods such as bananas, oranges, potatoes, and spinach, making it an important part of a balanced diet.