Gas discharge refers to the process where an electric current passes through a gas, causing it to emit light and heat. This phenomenon occurs when the gas is ionized, meaning that the atoms lose or gain electrons, creating charged particles. Common examples of gas discharge include neon signs and fluorescent lamps, where the gas inside glows when electricity flows through it. In a gas discharge tube, the gas is usually at low pressure, allowing the electric current to travel easily. The emitted light can vary in color depending on the type of gas used, such as neon for red or argon for blue. This technology is widely used in lighting and display applications.