 Climate change, energy efficiency, new trends in electricity markets, the obsolescence of the traditional electricity model, and the gradual transition of consumers to prosumer profiles are the main drivers of progressive change in electricity systems, towards the smart grid paradigm. The introduction of multiple distributed generation and storage resources with a strong emphasis on renewables necessitates advanced metering systems, such as smart meters, which can manage and control these distributed resources. Different technologies and standards have been proposed for smart metering systems, but they all share common characteristics. This paper reviews the key components of smart metering systems, discusses the deployment of these systems around the world, and summarizes the current trends in smart metering use and deployment. This article was authored by Noelia Oribe Perez, Luis Hernandez, David de la Vega, and others.