Supersonic speed refers to a speed greater than that of sound. A bullet fired from a modern-day gun is said to have this kind of speed. Another important example is the supersonic aircraft.
As the name suggests, they are flights that travel faster than sound. Historically, they were developed in the second half of the 20th century. It is said that US Air Force Captain Charles E. ‘Chuck’ Yeager was the first person to fly an aircraft faster than the speed of sound, in 1947.
One of the earliest and supersonic flights that was used as a passenger aeroplane was the Concorde. Its speed was twice the speed of sound, and was said to fly between London and New York in around three and a half hours! However, the flight is no longer used.
An Indian example of a supersonic flight is the HAL Tejas, which is still in service.