Backends

Backends, in computing, refer to the server-side components of an application that handle processing, business logic, data storage, and communication with clients. The backend runs on servers and is responsible for receiving requests from the client (frontend, mobile apps, or other services), executing logic, querying and updating databases, and returning data or status updates. It is distinct from the frontend, which runs in the user's browser or device and presents the user interface.

Core components include the application server, the database, and the API layer. The application server executes server-side code, enforces authentication and authorization, implements business rules, and orchestrates workflows. The database stores persistent data and includes relational systems (e.g., PostgreSQL, MySQL) and NoSQL stores (e.g., MongoDB, Redis). An API layer exposes endpoints (REST, GraphQL, or gRPC) for the frontend and other services. Caching, messaging queues, and search indexes may be used to improve performance and scalability.

Architectures vary from monolithic backends to microservices or serverless designs. In a monolith, a single codebase handles all backend functionality; in microservices, discrete services own specific domains and communicate over networks. Serverless models run small functions in managed environments, scaling automatically.

Operational concerns include deployment, monitoring, and security. Backends are deployed on virtual machines, containers (Docker), or cloud platforms, often using orchestration (Kubernetes). Important considerations include load balancing, fault tolerance, data integrity, authentication, authorization, encryption, and auditing.

Backends interact with frontends by providing data and services via APIs. They support web, mobile, and third-party integrations, and are developed with various languages and frameworks such as Java, Python, JavaScript/Node.js, Ruby, PHP, or .NET. Development practices include testing, version control, and continuous integration and deployment.