Azetidinecarboxylic acid, also known as proline, is an essential amino acid that plays a crucial role in various biochemical processes in the human body. This amino acid is involved in protein synthesis, wound healing, collagen formation, and immune function. Proline is also recognized as a non-essential amino acid, as it can be synthesized by the body, but it is also present in certain food sources like meat, dairy, and wheat. Additionally, proline serves as a precursor for the synthesis of hydroxyproline, a critical component of collagen. Hence, proline and azetidinecarboxylic acid are interchangeable terms for the same amino acid with multiple vital functions within the body.