The common bile duct is a tube that carries bile from the liver and gallbladder to the small intestine. Bile is a digestive fluid that helps break down fats. The duct is formed by the merging of the cystic duct from the gallbladder and the common hepatic duct from the liver. This duct plays a crucial role in digestion, especially after eating fatty foods. If the common bile duct becomes blocked, it can lead to serious health issues, such as jaundice or pancreatitis. Medical procedures, like an endoscopic retrograde cholangiopancreatography (ERCP), can help diagnose and treat such blockages.