  Thick disks appear to be common in external large spiral galaxies and our own
Milky Way also hosts one. The existence of a thick disk is possibly directly
linked to the formation history of the host galaxy and if its properties is
known it can constrain models of galaxy formation and help us to better
understand galaxy formation and evolution. This brief review attempts to
highlight some of the characteristics of the Galactic thick disk and how it
relates to other stellar populations such as the thin disk and the Galactic
bulge. Focus has been put on results from high-resolution spectroscopic data
obtained during the last 10 to 15 years.
