EBS is a block-based storage system for mounting volumes.

EBS volumes are independent of the EC2 instance - these volumes are logically , rather than directly, attached to the instance

By default a Root EBS is deleted when an instance is terminated, non-root are not deleted by default. Both settings can be changed.

EBS volume itself is only available in a single AZ and can be accessed by instances ONLY from the same AZ.

If you need access from instances in other AZ you can recreate volume from a snapshot and attach it to another instance in another AZ.

You can have multiple EBS volumes attached to an instance, but each EBS can be attached to one instance only