Which AWS service provides block storage primarily for EC2 instances?

Amazon EBS, or Elastic Block Store, is designed specifically to provide block storage for EC2 instances. It allows users to create storage volumes that can be attached to EC2 instances, enabling those instances to access data persistently. This service is integral for applications that require consistent and low-latency access to data, such as databases or data processing applications.

EBS volumes can be easily created, attached, detached, and modified while the EC2 instance is running, providing flexibility and scalability to adapt to storage needs over time. Additionally, EBS supports snapshots, which allow for data backup and recovery, further enhancing its utility for developers.

In contrast, Amazon S3 is an object storage service, primarily used for storing and retrieving any amount of data from anywhere in the web, yet it does not provide the block-level access that EBS does. AWS Lambda is a compute service that runs code in response to events, but it does not offer any storage capabilities in the same way EBS does. Amazon RDS is a managed relational database service, which can use EBS for underlying storage, but it is not a direct storage solution for EC2 instances itself.