S100 proteins are a family of small calcium-binding proteins that play important roles in various cellular processes. They are primarily found in the nervous system and muscle tissue, where they help regulate functions such as cell growth, differentiation, and inflammation. These proteins are characterized by their ability to bind calcium ions, which influences their activity and interactions with other proteins. Abnormal levels of S100 proteins have been associated with several diseases, including cancer and neurodegenerative disorders, making them potential biomarkers for diagnosis and therapeutic targets.