Amazon Simple Database Service (SimpleDB), also known as a key value data store, is a highly available and flexible non-relational database that allows developers to request and store data, with minimal database management and administrative responsibility.
SimpleDB provides a URL endpoint to guarantee encrypted messages between an application and a domain. In conjunction with AWS Identity and Access Management, you can create permissions for groups and users to specific SimpleDB domains. Amazon SimpleDB works with other Amazon services to give developers the ability to store their data in Amazon Simple Queue Service and run their applications in Amazon Elastic Compute Cloud.
Because Amazon SimpleDB provides scaling, customers only pay for resources used and not for compute resources when they aren’t actively being used.