Immunology is a branch of biomedical science that studies the immune system, which is responsible for defending our body against infections and diseases. It investigates how the immune system works to recognize and eliminate foreign substances such as bacteria, viruses, fungi, parasites or other pathogens that may cause illnesses. Immunology also looks at ways to boost the immune response when it is weakened due to disease or medical treatments like chemotherapy. The study of immunology helps researchers develop vaccines and therapies for various diseases, as well as understand autoimmune disorders where the body's own immune system mistakenly attacks its cells.