A standard incandescent lamp consists of a fairly large, thin, frosted glass envelope. Inside the glass is an inert gas such as argon and/or nitrogen. At the center of the lamp is a tungsten filament. Electricity heats the filament. The heated tungsten emits visible light in a process called incandescence.
Most standard light bulbs are incandescent lamps. They have a CRI of 100 and CCTs between 2600-3000 making them attractive lighting sources for many applications (about CRI and CCT). However, these bulbs are typically inefficient, converting only about 10% of the energy into light while transforming the rest into heat.
Another type of incandescent lamp is the halogen lamp. Halogen lamps also have a CRI of 100. But they're slightly more energy efficient, and they maintain their light output over time. A halogen lamp also uses a tungsten filament. However, the filament is encased inside a much smaller quartz envelope. And the gas inside the envelope is from the halogen group. If the temperature is high enough, the halogen gas will combine with tungsten atoms as they evaporate and redeposit them on the filament. This recycling process lets the filament last a lot longer. In addition, it's now possible to run the filament hotter. This means you get more light per unit of energy. Because the quartz envelope is so close to the filament, it becomes about four times hotter than a standard incandescent lamp.
As a result of this wasted heat energy, halogen lamps-popular in torchieres-really aren't too energy efficient. The exposed heat from halogen torchieres can also pose a serious fire risk, especially near flammable objects. Today, because of their inefficiency and risk, manufacturers have developed torchieres that can use other lamps, such as compact fluorescent lamps.