The spectrum is unique to the material and enables you to identify it.
It is important to note that, although a full understanding of the vibrational modes is of interest, you rarely need this as you can use a reference database for identification.
Recently it is becoming very popular that Raman spectrum are measured at every point in area and microscope image at certain spectrum band is reconstructed to see distribution of spectral information.
Raman instrument that has an ablitiy to show Raman spectral image is called Raman microscope.
The frequencies of vibration depend on the masses of the atoms involved and the strength of the bonds between them. Light atoms and strong bonds have high Raman shifts.