"Parakeet" is a general name given to small long-tailed species of parrot, usually originating from Asia or Australia. In North America, "parakeet" without further description (i.e. Indian Ringneck Parakeet, Grass Parakeet, Slaty-Headed Parakeet) has come to mean budgerigars, commonly known as budgies. While budgerigars are small, they are parrots and just as smart, active and social as larger species. They need a large cage plus daily time out of their cage to fly around, plenty of toys and foraging activities to keep their brains busy, and daily interaction with humans, other budgies(or both to meet their social needs.
Budgies often get a raw deal because they are small and often inexpensive, but there are many great fans of budgies on this forum! The fact that they are small means that it's possible to set up a really spacious enclosure for them with plenty of fun enrichment. Most cages intended for budgies are depressingly small and totally unsuitable - however, flight cages are often available and provide much more space.
Like all parrots, budgies can be noisy, messy and destructive. They need an excellent diet of pellets, seed and vegetables. A budgie whose cues are ignored will learn to bite. They require medical attention from avian veterinary specialists which can be expensive and difficult to locate. They are parrots just like their larger cousins, and will be much happier if they are treated with the same care and respect.