What Are Microservices?

Microservices are small, independent components of an application that each perform a specific task. They communicate with one another through APIs to form a complete system.

Microservices use APIs or message queues for communication. Synchronous methods like HTTP or gRPC handle real-time requests, while asynchronous messaging systems like Kafka improve scalability and reduce network latency.

Because microservices are isolated, a failure in one service does not bring down the entire application. Techniques such as retries and circuit breakers further enhance fault tolerance and overall system resilience.

MongoDB supports independent data stores for each service with flexible schemas, built-in redundancy, and global scalability. These features align with the distributed, independently deployable nature of microservices architectures.

A monolithic application is a single, unified codebase that must be deployed as one unit. In contrast, microservices divide functionality into smaller, independent services that can be developed, deployed, and scaled separately.

Microservices can be tested using standard software testing methodologies—unit tests for internal logic, integration tests for APIs and data stores, and end-to-end testing for functionality. A good strategy involves test automation via CI/CD pipelines.