The PPD (Purified Protein Derivative) test is administered to assess whether an individual has been exposed to Mycobacterium tuberculosis, the bacterium that causes tuberculosis, and if the body has developed an immune response against it. Tuberculosis is a contagious and potentially fatal infectious disease that can severely affect the lungs, kidneys, and other organs. This test holds critical importance for the early diagnosis of the disease and the protection of public health.