Amazon Elastic Block Store (Amazon EBS) provides block level storage volumes for use with EC2 instances.
EBS volumes behave like raw, unformatted block devices.
You can mount these volumes as devices on your instances.
EBS volumes that are attached to an instance are exposed as storage volumes that persist independently from the life of the instance.
You can create a file system on top of these volumes, or use them in any way you would use a block device (such as a hard drive).
AWS recommend Amazon EBS for data that must be quickly accessible and requires long-term persistence.
EBS volumes are particularly well-suited for use as the primary storage for file systems, databases, or for any applications that require fine granular updates and access to raw, unformatted, block-level storage.
To make a volume available outside of the Availability Zone, you can create a snapshot and restore that snapshot to a new volume anywhere in that Region.
EBS Volumes - Availability Zone
Amazon EBS volume is tied to its Availability Zone.
It can only be attached to instances in the same Availability Zone.
EBS Snapshot - Regional
An EBS snapshot is tied to its region.
It can only be used to create volumes in the same region and has to be copied from one region to another if needed.
AWS Free Tier includes 30GB of Storage, 2 million I/Os, and 1GB of snapshot storage with Amazon EBS.
With Amazon EBS, you pay for what you provisioned; it doesn't matter if you used it or not.