The immune system is a complex network of cells, tissues, and organs that are found throughout the body. Some of the key components of the immune system include:

1. Bone marrow: This is the soft tissue inside bones where blood cells, including immune cells, are produced.
2. Thymus: This is a gland located in the chest that participates in the maturation and activation of T cells, which are a type of white blood cell that play a crucial role in the immune response.
3. Lymph nodes: These are small, bean-shaped structures found throughout the body that filter the lymphatic fluid and contain immune cells, such as T cells and B cells.
4. Spleen: This is an organ located in the abdomen that filters the blood and stores immune cells, such as red blood cells, platelets, and immune cells.
5. Lymphatic vessels: These are vessels that transport lymphatic fluid, which carries waste and debris, as well as immune cells, throughout the body.
6. Tonsils and adenoids: These are collections of lymphoid tissue in the throat that help to filter inhaled air and prevent infections from spreading to other parts of the body.

These are some of the main components of the immune system, but immune cells are also found throughout the body, including in the blood, skin, and mucosal surfaces, such as in the lining of the gut and respiratory tract.