Final answer:
Homologous structures are shared physical features due to a common ancestor.
Step-by-step explanation:
Homologous structures are shared physical features due to a common ancestor. They are evidence of evolution and indicate that organisms share a common origin. These structures have similar underlying anatomical patterns but may have different functions in different species. For example, the bones in the wings of bats and birds are homologous structures even though they serve different purposes.