The smart grid is an extremely complex system of immense importance in people's modern lives. The modernisation of the smart grid has a direct impact on economic, political, and social aspects. While the modernisation of the electricity infrastructure has many benefits, it also brings many new threats. In addition, one must consider the increasing number of attacks on the smart grid, such as cyber security attacks, physical blackouts, and false data injection attacks. This article will describe how sensor monitoring can be used to improve the security of the smart grid, as well as Internet-based change attacks against the smart grid. Finally, future developments and potential problems for the smart grid are presented and discussed.