Homologous organs are defined as the organs of different animals that are having a similar structure but differ in their functions.
Example – Forelimbs of frog, man, and the flippers of the whale.
The structure of all these animals are same but the functions are different. The flippers are used for swimming, the forelimbs of frogs are used for jumping and propping, and the forelimbs of man are used for writing, eating, holding things, etc. Having a similar structure shows that all these animals have a common ancestor.