The article gives an overall description of electric transmission systems and the current challenges and changes these systems are facing. Changes are driven by both new commercial and political environment as well as technology changes. This article focuses on the technical aspects that are indirectly driven by the other aspects. This article describes how different technical solutions can be used to manage and mitigate challenges. This covers both HVDC (high voltage direct current) solutions and a number of FACTS (flexible AC transmission system) solutions. Finally, some reflections on the future of electric transmission system are given.