Serverless architecture, also known as Function as a Service (FaaS), allows developers to execute custom code in ephemeral containers managed by third-party services, eliminating the need for server management and scaling. This architecture is event-driven, meaning functions are triggered by specific actions within an application, contrasting with traditional models that require manual server scaling and maintenance. Platforms like AWS Lambda, Google Cloud Functions, and Azure Functions exemplify serverless solutions, offering automatic scaling, logging, and monitoring. AWS Lambda, in particular, charges based on compute time, providing a cost-effective solution by only billing for the time the code runs. Developers can deploy functions using AWS CLI and package their applications with tools like Maven to create deployment packages. The blog illustrates building a Java application for AWS Lambda, highlighting the process of creating, testing, and updating Lambda functions, including storing JSON documents in Couchbase, and emphasizes the benefits of serverless architectures such as scalability, reduced costs, and simplified back-end management.