Gravitational Lenses

1 Introduction.- 2 Basic facts and the observational situation.- 3 Optics in curved spacetime.- 4 Derivation of the lens equation.- 5 Properties of the lens mapping.- 6 Lensing near critical points.- 7 Wave optics in gravitational lensing.- 8 Simple lens models.- 9 Multiple light deflection.- 10 Numerical methods.- 11 Statistical gravitational lensing: General considerations.- 12 Statistical gravitational lensing: Applications.- 13 Gravitational lenses as astrophysical tools.- References.- Index of Individual Objects.