Which service allows you to run code without provisioning servers?

AWS Lambda is the service that enables you to run code without the need to provision or manage servers. This serverless architecture allows you to focus on writing your application code while AWS takes care of the underlying infrastructure. With Lambda, you can create functions that are triggered by various AWS services or HTTP requests, and these functions scale automatically based on the demand.

This model eliminates the need for you to specify the server configuration or manage the scaling, as Lambda automatically allocates the necessary compute resources. You only pay for the compute time that you consume, making it a cost-effective solution for occasional or variable workloads.

In contrast, other services like Amazon EC2 require you to provision and manage instances, involving explicit configuration for computing resources, which adds complexity and effort in resource management. Options such as Amazon ECS also require management of containerized applications on a cluster of servers, while Amazon S3 is primarily a storage service and does not directly execute code. Thus, AWS Lambda stands out as the ideal choice for running code without the server management overhead.