Potassium Ferrocyanide is a chemical compound with the formula K4[Fe(CN)6]. It appears as a yellow crystalline solid and is commonly used in various applications, including as a food additive and in the production of dyes. It is also known for its role in the laboratory as a reagent in chemical analysis. This compound is often referred to as "yellow prussiate of potash." Despite containing cyanide groups, it is considered safe for use in food and other applications because the cyanide is tightly bound within the structure and does not release toxic cyanide ions under normal conditions.