  Aims. M 31 has been completely imaged for the first time obtaining a
luminosity lower limit ~10^35 erg s-1 in the 0.2-4.5 keV band. Our XMM-Newton
EPIC survey combines archival observations with observations taken between June
2006 and February 2008. The main goal of the paper is a study of the X-ray
source population of M 31. Methods. An X-ray catalogue of 1897 sources was
created; 914 were detected for the first time. Source classification and
identification were based on X-ray hardness ratios, spatial extent of the
sources, and by cross correlating with catalogues in the X-ray, optical,
infrared and radio wavelengths. We also analysed the long-term variability of
the X-ray sources. Results. Fourteen of the 30 supersoft source candidates
represent supersoft emission of optical novae. Many of the 25 supernova
remnants (SNRs) and 31 SNR candidates lie within the 10 kpc dust ring and other
star forming regions in M 31; this connection between SNRs and star forming
regions implies that most of the remnants originate in type II supernovae. The
brightest sources in X-rays in M 31 belong to the class of X-ray binaries
(XRBs). Ten low mass XRBs (LMXBs) and 26 LMXB candidates were identified based
on their temporal variability. In addition 36 LMXBs and 17 LMXB candidates were
identified due to correlations with globular clusters and globular cluster
candidates. From optical and X-ray colour-colour diagrams, possible high mass
XRB (HMXB) candidates were selected. Two of these candidates have an X-ray
spectrum as is expected for an HMXB containing a neutron star primary.
Conclusions. While our survey has greatly improved our understanding of the
X-ray source populations in M 31, at this point 65% of the sources can still
only be classified as "hard" sources. Deeper observations in X-ray and at other
wavelengths would help classify these sources. ABRIDGED
