The 2 architectural approaches that use remote APIs most are service-oriented architecture (SOA) and microservices architecture. SOA, the oldest of the 2 approaches, began as an improvement to monolithic apps. Whereas a single monolithic app does everything, some functions can be supplied by different apps that are loosely coupled through an integration pattern, like an enterprise service bus (ESB).
While SOA is, in most respects, simpler than a monolithic architecture, it carries a risk of cascading changes throughout the environment if component interactions are not clearly understood. This additional complexity reintroduces some of the problems SOA sought to remedy.
Microservices architectures are similar to SOA patterns in their use of specialized, loosely coupled services. But they go even further in breaking down traditional architectures. The services within the microservices architecture use a common messaging framework, like RESTful APIs. They use RESTful APIs to communicate with each other without difficult data conversion transactions or additional integration layers. Using RESTful APIs allows, and even encourages, faster delivery of new features and updates. Each service is discrete. One service can be replaced, enhanced, or dropped without affecting any other service in the architecture. This lightweight architecture helps optimize distributed or cloud resources and supports dynamic scalability for individual services.