What is a microgrid and its advantages/disadvantages to our current electricity grid?

The electric-utility business is going through a major business process reengineering (BPR), stemming from technology improvements, economic forces, and public awareness.  The electricity sector is transforming from large plants that produce hundreds or thousands of megawatts of power that are sent to users through distribution grids, thanks to factors including lower cost natural gas and solar power.  Other factors include advanced control systems; more compact, smarter, and efficient electrical inverters; smart electricity meters and the growing Internet of Things; and the ever-growing ability to extract actionable information from big data.

Use this forum to discuss solar power as an alternate to electricity.  Although solar panels for most homes is not yet cost effective, discuss government subsidies that aim to put solar panels on more rooftops.  What is ‘community solar’ and would you join such an initiative?  What is a microgrid and its advantages/disadvantages to our current electricity grid?