A smart meter is a device that can read the consumption of electricity, gas or water in a building and reports it directly, using the internet, to the supplier. They can track how much is consumed at which point in time and report any unusual activities. Additionally, there is no need to estimate prices anymore for consumption, as real-time data is available from the smart meters.
The smart meter includes a device that is connected to the sources where it measures the energy consumption itself. A display that can track the data and visualize it is often also included or can be bought later on.