Answer
DynamoDB Streams captures a time ordered sequence of item level changes, including inserts, updates, and deletes, made to a table, and this stream can trigger a Lambda function automatically whenever a change occurs, making it a popular way to build event driven workflows like sending notifications, replicating data to another system, or maintaining derived aggregated tables.
aws dynamodb update-table --table-name Orders --stream-specification StreamEnabled=true,StreamViewType=NEW_AND_OLD_IMAGESReal-world example An inventory system uses a DynamoDB Stream connected to a Lambda function to automatically send a low stock alert notification the moment a product's quantity attribute drops below a certain threshold.