This article delves into the realm of building highly scalable applications using serverless computing technologies such as AWS Lambda, Azure Functions, or Google Cloud Functions. It outlines best practices including decomposing applications into microservices, leveraging asynchronous processing, optimizing function size and execution time, utilizing managed services, implementing auto-scaling and load balancing, and employing caching and content delivery. Furthermore, it discusses architectural patterns such as event sourcing, CQRS, saga pattern, and fan-out/fan-in for designing scalable serverless applications. By following these guidelines and embracing serverless computing, developers can create applications that effortlessly scale to meet growing demands and fluctuating workloads, while focusing on building innovative solutions without the burden of infrastructure management.