The other day, through one of our service technicians, a question was brought up by a customer that made me realize that there's probably not many people that fully understand what exactly a watt is.  Everyone knows that a 100W bulb is brighter than a 60W bulb, but that's probably the extent of it.

A watt is not a measure of how much light is produced by a bulb.  That would be a lumen.  A watt is a simple measurement of how much power/energy is consumed in one hour. 

For example, a 100W bulb will burn 100W of power in one hour.

This helps when looking at your utility bill and getting a better understanding of what you're paying for; but, more on that later.

-Byron