Penguins are birds - but even though they have wings they can't fly. Their wings are specially adapted for swimming.
Not all penguins live in snowy places like Antarctica. Some species like the Galapagos penguin live in warmer climates near South America.
The emperor penguin is the largest penguin, standing at more than a metre tall when fully grown. Male emperor penguins are responsible for looking after eggs until the chicks hatch.
The smallest penguin is called the fairy penguin. It is found quite commonly in Australia and New Zealand.
Ever wondered why they're black and white? Their dark back makes them hard to see from above while they're in the water, which can help protect them from predators.
To celebrate the arrival of three baby Humboldt penguins at Oregon zoo in the United States, here are Newsround's top five penguin facts!