Anatomy of an Amazon EC2 Resource ID
http://www.jackofallclouds.com/2009/09/anatomy-of-an-amazon-ec2-resource-id/
Each time you allocate a resource using EC2 – an instance, a volume or a snapshot – you receive a unique identifier. This is the EC2 resource ID. Have you ever wondered what this ID represents? Well, I did. After noticing similarities between the IDs of resources requested in close succession, I started digging.