To foster sustainable, low-emission development, many countries are establishing ambitious renewable energy targets for their electricity supply. Because solar and wind tend to be more variable and uncertain than conventional sources, meeting these targets will involve changes to power system planning and operations. Grid integration is the practice of developing efficient ways to deliver variable renewable energy (VRE) to the grid. Good integration methods maximize the cost effectiveness of incorporating VRE into the power system while maintaining or increasing system stability and reliability. This fact sheet includes sections titled, New Renewable Energy Generation, New Transmission, Increased System Flexibility, and Planning for a High Re Future. It also includes a list of grid integration terminology.