Gartner defines WAN optimization tools as products that improve the performance of applications running across the WAN as well as reduce WAN service expenses. WAN optimization solutions continue to evolve, and now support four high-level needs: improving the response times for users of business-critical applications over WAN links or mobile connections; assisting in maximizing ROI for WAN bandwidth; optimizing data-center-to-data-center (DC-to-DC) traffic for faster storage replication and synchronization; and assisting in directing traffic across multiple WANS, such as a hybrid WAN or public cloud connectivity.