FT-IR spectroscopy works by passing infrared light through a sample and measuring the vibrations between the bonds of its molecules. An FT-IR instrument uses an interferometer containing a beamsplitter and mirrors to simultaneously collect data for all wavelengths, which is then processed using Fourier transform into an infrared spectrum. The locations of peaks in the spectrum indicate the types of bonds present and can be used to identify functional groups and molecular structure. Applications of FT-IR spectroscopy in the pharmaceutical industry include drug research, formulation development and validation, quality control, and packaging testing.