  The dark matter of our galactic halo may be constituted by elementary
particles that interact weakly with ordinary matter (WIMPs). In spite of the
very low counting rates expected for these dark matter particles to scatter off
nuclei in a laboratory detector, such direct WIMP searches are possible and are
experimentally carried out at present. An introduction to the theoretical
ingredients entering the counting rates predictions, together with a short
discussion of the major theoretical uncertainties, is here presented.
