When buying eco-friendly lightbulbs, the pertinent terms you should know in order to understand how light bulbs actually work are watts and lumens. Watts are the amount of power needed to keep a bulb operating, and lumens are the amount of light emitted by a bulb.

Sylvania Soft White 60-Watt: $1.98 for a Pack of Four

• How it works: Electricity electrifies a tungsten filament, which glows when it gets hot, producing a warm light.
  
  
• These bulbs last about 1,000 hours and aren't very energy-efficient. About 90 percent of the energy they consume is emitted as heat, not light.
  
  
• Colors are typically soft white or "daylight." Daylight is whiter (less yellow).

TCP Springlight/Soft White: $4.97 Each

• How it works: light is produced by running electricity through a glass tube that contains mercury vapor and argon. The electricity activates mercury vapor, creating ultraviolet radiation that causes a phosphor coating on the inside of the glass to produce light. Because of the toxicity of the mercury they contain, they must be disposed of properly or recycled.
  
  
• This bulb, which was voted among the most pleasing by the New York Times panel, has roughly the same light output as an incandescent, but uses only 13 or 14 watts of energy to keep running.

GE Energy Smart 60-Watt Dimmable: $11.99 to $13.99 Each

• One thing that made it hard for people to switch to CFLs in the past was that they didn't work with dimmers. Now, manufacturers are introducing a bunch of these bulbs. They don't, however, work exactly the same way as incandescents.
  

Philips Halogena: $9.97 for a Pack of Two

• How it works: This bulb is a form of incandescent lighting that uses tungsten filaments, but they are contained in a small glass capsule along with halogen gases, which trap evaporating tungsten and redeposit it on the filament, enabling halogen bulbs to last twice as long as traditional incandescent bulbs.
  
  
• Even though they're more energy efficient than traditional incandescents, they're still far less efficient than CFLs.

American Lighting Ebulb: $49.99 Each

• How it works: These bulbs work like fluorescents, by stimulating mercury gas in a tube. Instead of using a constant flow of electricity to activate the gases, however, the electricity consumed stimulates an electromagnetic field exciting the gas, which then stimulates the phosphor to release the light.
  
  
• Induction technology has been around almost as long as incandescents. These are the lights used in tunnels.They consume less energy than compact fluorescents, and can last as much as five times longer -- but they're costly.

Lemnis Lighting Pharox Bulb: $59 Each

• How it works: This is an L.E.D. bulb. It uses semiconductor chips that produce light when electrified.
  
  
• These types of lights have been used for years in electronic gadgets like clock radios, and recently have begun appearing in residential lighting.
  

Resources
For more information on the featured light bulbs and on making the switch to eco-friendly light bulbs, visit nytimes.com.