Marsupials are mammals whose young are born at an early stage of development and typically complete much of their growth in a pouch.
After a short pregnancy, a newborn marsupial crawls from the birth canal to a teat, often with the help of its relatively well-developed forelimbs. It then remains attached while its organs, limbs, and nervous system continue developing. The pouch provides protection and a stable environment, although not every marsupial species has a deep or permanent pouch.
Kangaroos, koalas, wombats, possums, and bandicoots are marsupials. Most living marsupials are found in Australia and nearby New Guinea, but opossums are native to the Americas. Their reproductive strategy differs from that of placental mammals, or eutherians, whose young usually remain in the uterus longer and receive nourishment through a placenta.
Monotremes—such as the platypus and echidnas—are a separate mammal lineage that lays eggs. A common misconception is that all marsupials carry young in a pouch continuously; pouch shape, permanence, and use vary considerably among species.