DynamoDB is a hosted NoSQL database service offered by AWS that provides fast and scalable performance for applications with large amounts of data. It supports both document and key-value store models, has properties of both a database and a distributed hash table, and each table is synchronously replicated across three availability zones to ensure high availability and data durability. To correctly provision DynamoDB and keep applications running smoothly, it's essential to understand and track key performance metrics in various areas, including read and write queries, consumed capacity units, and errors. Monitoring these metrics can help identify issues before they impact application performance, such as latency, throttling, and errors. Additionally, monitoring Global Secondary Index creation and tuning provisioned capacities are crucial for maintaining good database health and performance. By tracking the right metrics and taking proactive measures, developers can ensure their applications run efficiently and effectively on DynamoDB.