25 years of using the spectroscopic method: where do we stand?

The spectroscopic technique, which consists in fitting high signal-to-noise optical spectra with the predictions of state-of-the-art model atmospheres, has routinely been used for over 25 years to measure the atmospheric parameters of DA white dwarfs, and DB stars as well. We review the technique, the progress we have made, and more importantly, we attempt to assess its validity and also try to identify some of the current challenges in the physics of white dwarf atmospheres related to the use of the spectroscopic technique.