At this website, the National Institute of Standards and Technology (NIST) offers the new Atomic Spectra Database Version 3.0, which "contains critically evaluated NIST data for radiative transitions and energy levels in atoms and atomic ions." Researchers can view the data by wavelengths or energy levels. Individuals can find articles summarizing the data and explaining the ground levels and ionization energies of neutral atoms. The website offers a useful help page as well as archives of NIST's previous versions of the database.