Which architecture involves building applications as small services?

Microservice Architecture is characterized by its approach to building applications as small, independent services that communicate over well-defined APIs. This architectural style allows for each service to be developed, deployed, and scaled independently, which fosters agility and flexibility in development. By breaking large applications into smaller, manageable pieces, teams can work on different services simultaneously and use varied technologies, optimizing each component's performance and traceability.

This architecture contrasts with Monolithic Architecture, where applications are built as a single unit, which can lead to challenges in maintaining and scaling. It also differs from Service-Oriented Architecture, which focuses on integrating large services that may still have substantial interdependencies, making them less modular than microservices. Serverless Architecture is primarily concerned with abstracting the server management aspect, allowing developers to focus on code execution without worrying about the infrastructure, but it does not specifically relate to the concept of small, autonomous services. Thus, Microservice Architecture stands out as the most suitable choice for developing applications with a modular, service-oriented approach.