Security Service Edge (SSE) platforms deliver cloud-native secure access to web, SaaS, and private applications by combining Secure Web Gateway (SWG), Cloud Access Security Broker (CASB), Zero Trust Network Access (ZTNA), and data protection into a single cloud-delivered service. Core capabilities include URL filtering and web threat inspection, SaaS application discovery and control with inline DLP, identity-aware private-application access (replacing legacy VPN), continuous posture and behavior assessment, and integration with the identity provider for contextual access decisions. SSE represents the security half of the SASE architecture, which separated from SD-WAN (the network half) because the buyer motion and deployment timeline differ. Leading vendors include Zscaler, Netskope, Palo Alto Prisma Access, Cisco Umbrella, Cato Networks, iboss, and Skyhigh Security.