The Mantoux test (also known as Tuberculin Skin Test or Purified Protein Derivative PPD) is a diagnostic tool for tuberculosis. It is a way to say if person has come in contact with tuberculosis. It does however tell us if that person is currently ill from tuberculosis. Like all tests there both false positive and false negative results.
A more modern method is the interferon-γ release assay -IGRA (QuantiFERON-TB Gold & T-SPOT.TB). It is made using a blood test.