White Noise

White noise is a kind of noise that is generated by combining sounds of all different frequencies jointly. In case you took all of the possible tones that a human can hear and combined them collectively, you would have white noise. 

The adjective “white” is used to illustrate this type of noise owing to the way white light works. White light is made up of all of the different colors (frequencies) of light combined together (a prism or a rainbow separates white light back into its component colors). Likewise, white noise is a blend of all the different frequencies of sound. You can believe of white noise as 20,000 tones all playing at the same time.