Far-infrared or Terahertz spectroscopy (THz) is a technique that identifies chemicals based on the interaction of molecules with electromagnetic radiation in the far-infrared or terahertz region (20-400 cm-1). Molecular absorbances of far-infrared light cause molecular rotations (similar to microwave radiation) and can be classified by chemical functional groups. The resulting THz spectrum produced is characteristic for a given molecule. Point analysis (“bench top”) systems are used for analyzing condensed phase materials, although some specialized systems are capable of analyzing gases in gas cells. THz spectra of pure materials can be searched against reference spectral databases, although an expert spectroscopist should examine data from any potential unknown mixtures. One strength THz spectroscopy offers is the ability to differentiate polymorphic differences readily compared to other optical spectroscopy (MIR, NIR, UV-Vis) methods. This lends the technique to analysis of pharmaceuticals, consumer products or any other material that has multiple polymorph forms.