What is Net Metering?

I came across a good read this week on Nerd Wallet that gets to the heart of net metering and why investor-owned utilities are so intent on curtailing it. If you have a few minutes, it's well worth a look: 

http://www.nerdwallet.com/blog/investing/2013/what-is-net-metering-solar-energy/

Here's a snippet to whet your appetite:

Obviously, NEM offers substantial utility cost savings to people who have made the investment in distributed energy sources, such as solar and wind energy technology for their homes. But it’s a misconception to think that they are the only ones benefiting from NEM. Studies show that net energy metering benefits all consumers and citizens...