Cosmology with gravitational lensing

Gravitational lensing effect is a classical prediction of general relativit y, but its application to cosmology has been recognized only relatively rec ently, The technology-driven developments in observational cosmology have s purred gravitational lensing events to the forefront of astronomy and they serve as valuable tools for measuring the cosmological parameters, for prob ing the dark matter in the universe and for constraining the cosmic scenari o of structure formation. We review the recent developments in this field, namely, the time-delay measurements, the masses of galaxies and clusters of galaxies and the cosmic shear.