The A4 experiment at MAMI

The A4 experiment at the MAMI accelerator facility at Mainz studies the nucleon structure by measuring beam single spin asymmetries in the electron-proton scattering. Longitudinal spin measurements, i.e. parity violating (PV), for accessing the strangeness contributions to the nucleon form factors, as well transverse spin measurements, sensitive to higher order QED corrections, have been performed on both hydrogen and deuterium targets at both forward and backward angles. A review of the experimental programme with emphasis on the recently published results and the ongoing data analysis activities is given. The status of the latest attempt of extracting the PV asymmetry from inclusive single-pion electroproduction in the invariant mass range from threshold to the maximum of the Δ(1232) resonance is reported.