Budgies are the third most popular pets in the world. Right after domestic dogs and cats.
Budgerigar parakeets originate from Australia. In the wild budgies live in the dry grasslands of Australia mostly eating grass seeds. Escaped pet budgies can have a feral existence on any continent, in some places joining flocks of other birds such as sparrows. In some warmer places such as in Florida feral budgies can form entire flocks of their own.
In the pet trade there are many color variations of budgies, some lacking yellow pigment thus having a blue plumage instead of the wild green coloration. But there are albino breeds lacking most of their pigments and having a generally white color.
Budgies like to eat seeds with a husk or shell that they can remove. This among other things includes millet, sunflower seeds, oats. They will also eat greens, pieces of fleshier vegetables, even hard boiled eggs.
Budgies even in captivity need a perch to rest on. They also need some space to fly.
Budgies will learn to imitate human speech but they are unlikely to actually understand it.
Further Readings:
Budgie Care 101.
Budgie Diet – the key to your budgie’s well being.
budgieplace.com
Budgerigar colour genetics on Wikipedia.