In what way homologous organs provide evidence for evolution ?

Explanation

The organs having common origin and structural similarity but different functions are called homologous organs. It can be said from their structural similarity that they have been evolved from a common ancestor. For example the forelimbs of frogs (amphibians), the forelimbs of lizards (reptiles), wings of birds (aves), the hands of human beings (mammals), etc. are homologous organs having similar structure.

The basic structure of the limbs is similar though it has been modified to perform different functions in various vertebrates.
Such a homologous characteristics helps to identify an evolutionary relationship between apparently different species.