The impact of gravitating lensing on astrophysics -- to basic concepts of gravitational lensing -- Optical observations of gravitational lenses -- Recent radio observations of gravitational lenses -- Old faithful: The venerable gravitational lens system 0957+561 -- Determining the Hubble parameter -- Time delay determination for the first gravitational lens Q0957+561 A,B -- Photometric monitoring of gravitational lenses with the nordic optical telescope -- A search for closely-spaced gravitational lenses -- A high-resolution imaging survey for gravitational lenses -- Search for gravitational lensing in a sample of highly luminous quasars -- Bidimensional spectrography of multiple quasars -- Sizing up the universe with an optical illusion: Comments on the measurement of ?t in Q 0957+561 -- HST observations of G2237+0305 and PG1115+080 -- A star-formation region in 2237+030 -- Redshift measurements of the brightest cluster galaxies of the gravitational lens 0957+561 -- The Triple Quasar PG1115+080 -- 1830-211 as a lens artefact -- 0218+357: The smallest separation lensed system -- Gravitational microlensing -- The search for massive compact halo objects -- Probing the galactic disk with gravitational microlensing -- Searching for microlensing in optical lightcurves of quasars -- The Hamburg quasar monitoring program at Calar Alto -- Microlensing predictions for the Einstein cross 2237+0305 -- Expected color variations of the microlensed QSO 2237+0305 -- Intrinsic variability implications for microlensing -- Gravitational lensing statistics -- Quasar-galaxy associations -- Associations between QSOs and galaxies -- Quasar-galaxy associations -- Einstein rings and related phenomena -- Observational indications for statistical lensing by clusters of galaxies -- Counts of galaxies around distant highly luminous QSOs -- A search for close separation (? 1?) quasar images -- Joint discussion on quasar-galaxy associations -- Luminous arcs: An observational update -- Cluster gravitational lenses -- Deep galaxy surveys -- Statistical lensing by clusters of galaxies and Dark Matter distribution -- Observation and analysis of Abell 2218 arcs and rings -- New results on Abell 963 and MG1131+0456 -- On the straight arc in A2390 -- A search for gravitational lenses using sky survey plate scans -- Gravitational lensing of BL Lac objects and related AGN -- Recent observations of PKS1830-211 -- Possible test for ? with gravitational lenses -- Gravitational lensing by large-scale structures -- Concluding summary -- Spectrography in the 0957+561 field -- Gravitational lensing in alternative cosmological models -- Possibilities for observing lensing effects in the gravitational field of our galaxy -- The appearance of cross-like quasar images and the estimation of GL parameters -- Gravitational lensing properties of the Reissner-Nordström type neutron star -- A search for the optical counterpart of the Einstein ring PKS 1830-211 -- Local behavior of caustics in different lens models -- Multiple imaging by gravitational waves -- Statistical lensing by extended lenses -- VLBI hybrid maps of 0957+561 A,B -- Deformation of P Cygni line profiles by gravitational microlensing effects -- Statistical lensing and the overdensity of QSO near foreground galaxies -- A moving gravitational lens in the Friedmann universe -- Strong microlensing and BL LAC objects -- Dispersive effects in the spectra of QSO pairs -- Our galactic nucleus through the lens's eye of gravity -- Unobserved lensing agents -- Discordant redshifts in compact groups of galaxies -- An analytical approach to quasar variability due to microlensing -- Morse theory and gravitational microlensing -- N-body techniques for ?-lensing -- Statistics of lensing by clusters of galaxies: Giant luminous arcs -- Spherical opaque gravitational lens models and their implication for ? 0 -- Catastrophe theory and stable images and caustics in gravitational lenses -- List of contributions not submitted for inclusion.