  The Apache Point Observatory Galactic Evolution Experiment (APOGEE), one of
the programs in the Sloan Digital Sky Survey III (SDSS-III), has now completed
its systematic, homogeneous spectroscopic survey sampling all major populations
of the Milky Way. After a three year observing campaign on the Sloan 2.5-m
Telescope, APOGEE has collected a half million high resolution (R~22,500), high
S/N (>100), infrared (1.51-1.70 microns) spectra for 146,000 stars, with time
series information via repeat visits to most of these stars. This paper
describes the motivations for the survey and its overall design---hardware,
field placement, target selection, operations---and gives an overview of these
aspects as well as the data reduction, analysis and products. An index is also
given to the complement of technical papers that describe various critical
survey components in detail. Finally, we discuss the achieved survey
performance and illustrate the variety of potential uses of the data products
by way of a number of science demonstrations, which span from time series
analysis of stellar spectral variations and radial velocity variations from
stellar companions, to spatial maps of kinematics, metallicity and abundance
patterns across the Galaxy and as a function of age, to new views of the
interstellar medium, the chemistry of star clusters, and the discovery of rare
stellar species. As part of SDSS-III Data Release 12, all of the APOGEE data
products are now publicly available.
