IFN, or Interferon, is a type of protein produced by the body in response to viral infections. It plays a crucial role in the immune system by signaling neighboring cells to enhance their defenses against viruses. There are several types of interferons, including IFN-alpha, IFN-beta, and IFN-gamma, each with specific functions in immune response. Interferons are also used as therapeutic agents in treating various diseases, including certain types of cancer and viral infections like Hepatitis C. They help boost the immune response and can inhibit viral replication, making them valuable in medical treatments.