See-quark effects in low energy observables are very important for the understanding of hadron structure, because they are a direct manifestation of QCD degrees of freedom in the non-perturbative regime. One example is the contribution of the strange quark to the electromagnetic form factors of the proton. This contribution can be parametrised in terms of the so called strangeness electric and magnetic vector form factors. The experimental access to such strangeness form factors via parity violating electron scattering and the today available data will be reviewed. The experimental challenges of such measurements and in particular the A4 experiment at MAMI (Mainz) will be presented. Finally, the latest published results from the A4 Collaboration will be discussed.
