The hydrogen emission spectrum is a series of colors emitted when a hydrogen atom is excited by a high voltage. These colors are created by hydrogen's electron gaining or losing energy and moving to different energy levels. The energy that an electron gains or loses appears as light.
Placing hydrogen in a hydrogen discharge tube and running a current through it creates a pink light. When the light is passed through a prism, various colors may be seen. The visible colors in the spectrum are only a small number of the colors created. The majority of the colors are in the infrared and ultraviolet ranges.