In the two decades since the discovery of the first double quasar, gravitational lensing has been applied in quite a number of astrophysical fields and turned out as a very useful astrophysical and cosmological tool. After a few historic remarks and a brief introduction into the basics of lensing, a few examples of strong lensing phenomena are shown. In the main part, four recent applications of lensing in astrophysics/cosmology are presented, namely the determination of the Hubble constant in the double quasar Q0957+561, microlensing of quasars and the conclusions on quasar size and dark matter objects, search for extrasolar planets with gravitational lensing, and the recent detection of very weak lensing.

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