What better way to kick off an idea website than with the light bulb. A 60 watt incandescent bulb from way back when (maybe 10 years now) will be used as the normal reference point. Watts mean the amount of power or energy the bulb uses. The electric bill totals the amount of kilowatt (1,000 watts) hours or kWh you use each month. A 60 watt bulb left on for 1 hour calculates to .06 kWh. Lumens are basically how bright is the bulb. The normal bulb is 800 lumens. Generally, if you need a brighter bulb, increase the wattage and the lumens will increase. Kelvin measures the color temperature and thus determines the color of the light. The basic yellowish light bulb, or classified as a soft warm light, is around 3,000 Kelvin. Bright or Cool White is around 4,000 Kelvin and Daylight is 5,000 Kelvin and above. Voltage measures the current. Most house fixtures use 120 Volts. Always double check the Voltage needed. 20 year cost will factor in the cost of the bulb and the cost of energy usage at 12 cents per kWh. Average usage for a main bulb will be about 3 hours a day for 365 days or conveniently 1,000 hours per year or 20,000 total hours for 20 years.