DynamoDB is a managed NoSQL database service provided by Amazon Web Services. As it is managed by Amazon, users do not have to worry about operations such as hardware provisioning, configuration, and scaling. The offering primarily targets key-value and document storage.
As Amazon runs an e-commerce platform for millions of concurrent users, the underlying services powering the platform must be highly reliable and scalable. Failures in infrastructure would have significant financial consequences and would degrade consumer trust in Amazon's platform. Thus, the motivating purpose behind DynamoDB was a data-store used by these services that could keep up in both availability and scalability such that infrastructure failures would not affect user experience. The original concept and implementation of DynamoDB was first introduced in 2007 with a paper titled: "Dynamo: Amazon’s Highly Available Key-value Store"
DynamoDB supports a pluggable local persistence engine that can range from in-memory buffers with persistent backing to purely disk-oriented ones. This allows it to be flexible with an application's access patterns.
DynamoDB is schemaless. Each table requires a primary key to identify its corresponding data item. However, there are no such constraints on non-key attributes. DynamoDB can hold both structured or semi-structured data, such as JSON or XML.