  In Galaxy And Mass Assembly Data Release 4 (GAMA DR4), we make available our
full spectroscopic redshift sample. This includes 248682 galaxy spectra, and,
in combination with earlier surveys, results in 330542 redshifts across five
sky regions covering ~250deg^2. The redshift density, is the highest available
over such a sustained area, has exceptionally high completeness (95 per cent to
r_KIDS=19.65mag), and is well suited for the study of galaxy mergers, galaxy
groups, and the low redshift (z<0.25) galaxy population. DR4 includes 32
value-added tables or Data Management Units (DMUs) that provide a number of
measured and derived data products including GALEX, ESO KiDS, ESO VIKING, WISE
and Herschel Space Observatory imaging. Within this release, we provide visual
morphologies for 15330 galaxies to z<0.08, photometric redshift estimates for
all 18million objects to r_KIDS~25mag, and stellar velocity dispersions for
111830 galaxies. We conclude by deriving the total galaxy stellar mass function
(GSMF) and its sub-division by morphological class (elliptical, compact-bulge
and disc, diffuse-bulge and disc, and disc only). This extends our previous
measurement of the total GSMF down to 10^6.75 M_sol h^-2_70 and we find a total
stellar mass density of rho_*=(2.97+/-0.04)x10^8 M_sol h_70 Mpc^-3 or
Omega_*=(2.17+/-0.03)x10^-3 h^-1_70. We conclude that at z<0.1, the Universe
has converted 4.9+/-0.1 per cent of the baryonic mass implied by Big Bang
Nucleosynthesis into stars that are gravitationally bound within the galaxy
population.
