Digital pianos are electronic musical instruments, intended to be an alternative to conventional pianos. These modern instruments imitate both sound and look of its antecessor, the string (conventional) piano.
They have become more popular over the years, since they are a lot more practical than the conventional piano. For example, they do not need tuning, which is great for those who are just learning to play or for amateurs, not very knowledgeable in the technical area of piano maintenance. They also come with additional features which lead to easier learning and allow you to compose.
Since the technological boom in the eighties, digital pianos and computers began to connect via MIDI to carry out a great deal of functions as are musical recording, musical notation and make computer generated sounds.
There are other instruments that may reproduce piano like sounds, but playing a digital piano (also known as keyboard) gives a real piano feel, since the keys are weighed as acoustic piano keys are, and sound fidelity is of higher quality.