A smart grid is an electrical grid which includes a variety of operation and energy measures including:

Advanced metering infrastructure (of which smart meters are a generic name for any utility side device even if it is more capable e.g. a fiber optic router)
Smart distribution boards and circuit breakers integrated with home control and demand response (behind the meter from utility perspective)
Load control switches and smart appliances, often financed by efficiency gains on municipal programs (e.g. PACE financing)
Renewable energy resources, including capacity to charge parked (electric vehicle) batteries or larger arrays of batteries recycled from these, or other energy storage.
Energy efficient resources
Sufficient utility grade fiber broadband to connect and monitor the above, with wireless as backup. Sufficient spare if "dark" capacity to ensure failover, often leased for revenue.Electronic power conditioning and control of the production and distribution of electricity are important aspects of the smart grid.Smart grid policy is organized in Europe as Smart Grid European Technology Platform. Policy in the United States is described in 42 U.S.C. ch. 152, subch. IX § 17381.
Roll-out of smart grid technology also implies a fundamental re-engineering of the electricity services industry, although typical usage of the term is focused on the technical infrastructure.