API gateways have been around for a long time as the entry point for clients to access the back-end, mainly to manage “north-south” traffic, In recent years, service mesh architectures have become popular, mainly for managing internal systems,(i.e. “east-west” traffic), while a service mesh like Istio also has built-in gateways that bring traffic inside and outside the system under unified control. This often creates confusion for first-time users of Istio. What is the relationship between the service mesh and the API gateway? How does Istio’s gateway work? What are the ways to expose the services in the Istio mesh? This article gives you the answer.