Serverless backend patterns enable event-driven, scalable application architectures where cloud providers manage infrastructure, allowing developers to focus on business logic while paying only for actual compute time. These patterns—built primarily on AWS Lambda, Azure Functions, and Google Cloud Functions—provide automatic scaling, high availability, and reduced operational overhead for modern cloud-native applications. The key to successful serverless backends lies in understanding function invocation models, optimizing cold start performance, designing stateless workflows, managing dependencies and secrets, and implementing robust error handling with idempotent operations. While provisioned concurrency and proper architecture patterns solve most performance concerns, the real power emerges when combining messaging services (SNS, SQS, EventBridge), API gateways, and orchestration tools (Step Functions) to build resilient distributed systems.