  VANDELS is a uniquely-deep spectroscopic survey of high-redshift galaxies
with the VIMOS spectrograph on ESO's Very Large Telescope (VLT). The survey has
obtained ultra-deep optical (0.48 < lambda < 1.0 micron) spectroscopy of ~2100
galaxies within the redshift interval 1.0 < z < 7.0, over a total area of ~0.2
sq. degrees centred on the CANDELS UDS and CDFS fields. Based on accurate
photometric redshift pre-selection, 85% of the galaxies targeted by VANDELS
were selected to be at z>=3. Exploiting the red sensitivity of the refurbished
VIMOS spectrograph, the fundamental aim of the survey is to provide the high
signal-to-noise ratio spectra necessary to measure key physical properties such
as stellar population ages, masses, metallicities and outflow velocities from
detailed absorption-line studies. Using integration times calculated to produce
an approximately constant signal-to-noise ratio (20 < t_int < 80 hours), the
VANDELS survey targeted: a) bright star-forming galaxies at 2.4 < z < 5.5, b)
massive quiescent galaxies at 1.0 < z < 2.5, c) fainter star-forming galaxies
at 3.0 < z < 7.0 and d) X-ray/Spitzer-selected active galactic nuclei and
Herschel-detected galaxies. By targeting two extragalactic survey fields with
superb multi-wavelength imaging data, VANDELS will produce a unique legacy data
set for exploring the physics underpinning high-redshift galaxy evolution. In
this paper we provide an overview of the VANDELS survey designed to support the
science exploitation of the first ESO public data release, focusing on the
scientific motivation, survey design and target selection.
