Tumor Necrosis Factor (TNF) is a protein produced by the immune system that plays a crucial role in inflammation and the body's response to infection. It helps regulate immune cells and can induce fever, cell death, and the formation of new blood vessels. TNF is essential for fighting off infections but can also contribute to inflammatory diseases when produced in excess. In conditions like rheumatoid arthritis and Crohn's disease, high levels of TNF can lead to chronic inflammation and tissue damage. Medications that block TNF, known as TNF inhibitors, are often used to treat these diseases, helping to reduce inflammation and improve patients' quality of life.