Microsoft Azure SQL Database is a fully managed platform-as-a-service (PaaS) database offering that supports both relational and non-relational data models. It provides various purchase models and service tiers to accommodate different types of workloads, including single databases, elastic pools, serverless databases, and more. Azure SQL Database generates telemetry data such as metrics, resource logs, and audit logs to help monitor performance and costs. Key performance metrics include compute, storage, request, and connectivity metrics, which provide insights into resource utilization, availability, and database traffic. Monitoring these metrics can help detect potential issues and optimize the configuration of Azure SQL databases for better performance and cost efficiency.