It's known as the compact fluorescent light.
Incandescent bulbs contain a wire filament.
The electric current flows through the wire, and as it does, the wire resists the flow of electrons. This causes the wire filament to get hot and it eventually glows. So, incandescent bulbs create both heat and light. CFLs contain gas instead of wire filaments. When electricity flows through this gas, it is converted to a form of energy that causes the phosphor-coated tubes to glow.