There are several applications of spectroscopy in the fields of medicine, physics, chemistry, and astronomy.  Taking advantage of the properties of absorbance and with astronomy emission, spectroscopy can be used to identify certain states of nature.  The uses of spectroscopy in so many different fields and for so many different applications has caused specialty scientific subfields. Such examples include:
* Determining the atomic structure of a sample
* Studying spectral emission lines of the sun and distant galaxies
* Space exploration
* Cure monitoring of composites using optical fibers.
* Estimating weathered wood exposure times using near infrared spectroscopy.
* Measurement of different compounds in food samples by absorption spectroscopy both in visible and infrared spectrum.
* Measurement of toxic compounds in blood samples
* Non-destructive elemental analysis by X-ray fluorescence.
* Electronic structure research with various spectroscopes.
* Redshift to determine the speed and velocity of a distant object
* Determining the metabolic structure of a muscle
* Monitoring dissolved oxygen content in freshwater and marine ecosystems
* Altering the structure of drugs to improve effectiveness
* Characterization of proteins
* Respiratory gas analysis in hospitals
* Finding the physical properties of a distant star or nearby exoplanet using the Relativistic Doppler effect.
* In-ovo sexing: spectroscopy allows to determine the sex of the egg while it is hatching. Developed by French and German companies, both countries decided to ban chick culling, mostly done through a macerator, in 2022.
* Process monitoring  in Industrial process control