Weak Lensing as a Probe of Dark Matter.

Weak gravitational lensing of distant galaxies can probe the total projected mass distribution of foreground gravitational structures on all scales and has been used successfully to map the projected mass distribution of rich intermediate redshift clusters. This paper reviews the general concepts of the lensing analysis. We focus on the relation between the observable (shapes and fluxes) and physical (mass, redshift) quantities and discuss some observational issues and recent developments on data analysis which appear promising for a better measurement of the lensing signatures (distortion and magnification) at very large scales.