Birds have feathers, wings, lay eggs and are warm blooded.
There are around 10000 different species of birds worldwide.
The ostrich is the largest bird in the world. It also lays the largest eggs and runs faster than any other animal on two legs, hitting speeds around 70 kph (43 mph).
Scientists believe that birds evolved from theropod dinosaurs.
Birds have hollow bones which help them fly.
Some bird species are intelligent enough to create and use tools.
The chicken is the most common species of bird found in the world.
Kiwis are endangered, flightless birds that live in New Zealand. They lay the largest eggs relative to their body size of any bird in the world.
Hummingbirds can fly backwards.
The bee hummingbird is the smallest living bird in the world, with a length of just 5 cm (2 in).
Around 20% of bird species migrate long distances every year.
Homing pigeons are bred to find their way home from long distances away and have been used for thousands of years to carry messages.