Abstract
Backend systems provide the execution, data, reliability, and security foundations of modern software services. This review summarizes the evolution from monolithic applications to RESTful APIs, microservices, event-driven systems, containers, orchestration platforms, and serverless computing. It also examines data management, distributed consistency, caching, scalability, tail latency, reliability engineering, observability, deployment practice, and security governance. The review argues that backend architecture is primarily a discipline of trade-off management: each design style improves some qualities while increasing complexity elsewhere. Future backend work will be shaped by platform engineering, AI-assisted systems, edge deployment, and stronger operational governance.
