Interferons are proteins produced by the body's cells in response to viral infections and other stimuli. They play a crucial role in the immune system by signaling neighboring cells to enhance their defenses against viruses. Interferons can also activate immune cells, such as T cells and natural killer cells, which help eliminate infected cells. There are three main types of interferons: Type I, Type II, and Type III. Each type has distinct functions and is produced by different cells. Interferons are also used in medical treatments for certain diseases, including some types of cancer and viral infections like hepatitis and multiple sclerosis.