What AWS service allows you to automatically scale an application based on demand?

AWS Auto Scaling is designed specifically to automatically adjust the number of compute resources used by your applications based on current demand. It enables you to set policies that monitor your application's performance, such as CPU usage, and scales your resources up or down in response. This automatic scaling helps maintain application performance and availability while optimizing costs, as you only pay for the resources you need when you need them.

This service is pivotal for workloads that experience varying traffic levels, ensuring that sufficient resources are allocated during peak times while scaling back during periods of lower demand. AWS Auto Scaling works in conjunction with other services like Amazon EC2, allowing you to maintain target utilization levels and the health of your applications.

In contrast, AWS Lambda is an event-driven, serverless computing service that automatically executes code in response to events and manages the compute resources for you, but it doesn’t specifically handle scaling applications in the traditional sense of resource management. AWS EC2 provides the virtual servers, but scaling must be managed either manually or through Auto Scaling. AWS CloudFormation is a service for infrastructure as code, which helps you define and provision AWS resources, but it does not inherently provide automatic scaling capabilities.