The parakeet has evolved to cope with life in the Australian outback. It is able to retain most of the liquid it acquires from its diet, preventing dehydration in its arid environment. Parakeet owners will notice that, when drinking, the birds take a little sip - and that's it! This is why it's important to give them fresh food and sprouting seeds, for the moisture content as much as anything else.
Parakeets, like all parrots, have distinctive four-toed feet, which they can use like hands for grasping things. The beak is like a third limb in many ways, assisting climbing, and able to open wide to grip objects. Look at the way your pet parakeet opens its beak - this type of beak is a parrot and parakeet speciality - most birds have the upper part of their beak fused to the skull, but the parrot family has a hinged upper beak, enabling it to open wide.
Wild budgerigars in Australia
Cock parakeets have stronger beaks than hens; but it's usually the females who routinely use their beaks in anger, usually in defence of their nest. Pet parakeets are generally placid, though, and very small, so the bird is incapable of inflicting damage on its owner. You will definitely feel it if an angry bird nips you, though!