Dolphins are capable of communicating using three or more different types of sounds. The main three are called "clicks", "bursts", and "whistles". They have been fount to have meaning and are capable of communicating between species of dolphin.
Below is a diagram of how the dolphin makes the sounds to communicate.
Dolphins are also found to play with each other. They are found to "joke fight", and to play with seaweed.
Click here to listen an example of a "burst".