Melena refers to the passage of black, tarry stools, which occurs when there is bleeding in the upper gastrointestinal tract, usually from the stomach or duodenum. The dark color and sticky consistency of melena result from the digestion of blood in the intestinal tract. Melena is often indicative of significant bleeding and may be associated with conditions such as peptic ulcers, gastric erosions, or gastrointestinal malignancies. Timely intervention is crucial to determine the underlying cause of bleeding and prevent further complications.