What is the main function of the thymus? 

The thymus is a gland located in the chest that plays a key role in the immune system by producing white blood cells (WBCs) such as T-lymphocytes (also known as T-cells), which are important for fighting off infections. T cells produced in the thymus help to recognize and destroy foreign invaders, such as bacteria, viruses, and cancer cells, and play a crucial role in the body's defense against disease.