The family Cuculidae, commonly known as cuckoos, includes a diverse group of birds found worldwide, except in extreme polar regions. They are known for their distinctive calls and behaviors, particularly brood parasitism, where some species lay their eggs in the nests of other birds, leaving them to raise their young. Cuckoos vary in size and color, with some species exhibiting striking plumage. They primarily inhabit forests, grasslands, and wetlands, feeding on insects, small animals, and fruits. Notable members of this family include the common cuckoo and the black-billed cuckoo, each playing unique roles in their ecosystems.