In addition to the traditional line-by-line spectroscopic absorption parameters, the HITRAN database contains information on absorption cross-sections where the line-by-line parameters are absent or incomplete. Typically HITRAN includes absorption cross-sections for heavy polyatomic molecules (with low-lying vibrational modes) which are difficult for detailed analysis due to the high density of the spectral bands/lines, broadening effects, isomerization, and overall modeling complexity. There are 327 molecular species in the current edition of the database provided as cross-section files. The cross-section files are provided in the HITRAN format described on the official HITRAN website (http://hitran.org/docs/cross-sections-definitions/).