An automated way for services in a cloud application to find and connect to each other without hardcoding addresses. Like a phone directory that automatically updates when people move — services register themselves and others look them up by name instead of memorizing addresses.
A streaming platform uses AWS Cloud Map so their video encoding, thumbnail generation, and recommendation microservices can automatically find each other as instances scale up and down, without anyone manually updating configuration files with new IP addresses.
AWS Cloud Map is a purpose-built service discovery registry that integrates with ECS/EKS and Route 53. Azure, GCP, and OCI commonly implement service discovery using private DNS (often paired with their container platforms like AKS/GKE/OKE) so services can resolve each other by name as endpoints change.