Dolphins are marine mammals belonging to the family Delphinidae, which includes around 40 species. They are known for their intelligence, social behavior, and acrobatic displays. Common species include the bottlenose dolphin, recognized for its friendly nature and often seen in aquariums and marine parks, and the orca, or killer whale, which is the largest member of the dolphin family. Dolphins inhabit oceans and rivers worldwide, with some species, like the Amazon river dolphin, living in freshwater environments. They communicate using a variety of clicks, whistles, and body movements, showcasing their complex social structures and relationships within pods.