Penguins (Spheniscidae) are a classification of flightless birds that thrive in aquatic locations in the Southern Hemisphere. They are commonly found on Antarctica, and live in various other locations such as the Galápagos Islands, Australia, Chile and more. Penguins are not very migratory, instead returning often to the areas they were born to mate and breed. They breed in large colonies, which characterizes the Spheniscidae as very social. Most penguins lay two eggs on average in their own cluth (nest), while species such as the Emperor or King penguins may only lay one.

Penguins have many differences in their physical appearance, which helps scientists identify the twenty or so types of species. For example, the Emperor penguin has a black head, chin, and throat with yellow ear patches while the Gentoo has a black head with white eyelids and triangular patches of white above each eye. All Spheniscidae have webbed feet and wings that are used as flippers to navigate through water with ease. While penguins waddle and can approach speeds around 2.5 mph on land, they are very agile in the water. This aids in catching food and avoiding predators such as the sea lion (Otaria flavescens).

The average life span of the penguin is between fifteen and twenty years. One of the main sources of death is lack of food, in the case of parents not being able to provide for their offspring. Chicks have a very low survival rate among all species of Spheniscidae. They have many predators that dwell in the water and other land species such as foxes (Alopex) and petrels (Pagodroma nivea) will often try to steal eggs from unsuspecting penguins.