  We review the state of our knowledge concerning the contribution of strange
quarks to various nucleon properties. In the case of the electric and magnetic
form factors, the level of agreement between theory and experiment is very
satisfactory and gives us considerable confidence in our capacity to make
reliable calculations within non-perturbative QCD. In view of the importance of
the scalar form factors to the detection of dark matter candidates such as
neutralinos, we place a particular emphasis on the determination of the pi-N
and strange quark sigma commutators.
