Rather than exposing services directly, organizations place a gateway at the edge: it terminates connections, validates tokens and keys, applies quotas and throttling, transforms requests, and produces telemetry. In microservice and cloud architectures it becomes a policy enforcement point for east-west and north-south API traffic.
Key points
Consistent edge policyAuthentication, authorization scopes, schema validation, rate limits, and logging belong at the gateway rather than being reimplemented per service.
High-value infrastructureIt sees every request and holds keys — protect its administrative plane, patch it, and monitor it like an identity system.
Important limitationA gateway routes and filters; it does not make the API secure. Authorization logic flaws, excessive data exposure, and backend trust of gateway-forwarded requests remain behind the gateway — and a misconfigured gateway is a single point of failure for every API it serves.