The three bodies consist of sheaths that correspond to the five elements in their subtle form.  These are energetic layers, fields of vibration, whose functions become more and more subtle.  Each sheath is a layer in our existence.

These five sheaths are called Koshas.  Kosha means sheath or covering.  Each sheath is a physical manifestation of creation.  The five koshas are the: annamaya kosha, the pranamaya kosha, manomay kosha, vijnanamay kosha, and the anandamaya kosha.