A detailed walkthrough of Azure Cosmos DB cost optimization strategies. Covers the three billing models: free tier, provisioned (manual vs. autoscale), and serverless, explaining when each makes sense. Autoscale is recommended for nearly all workloads due to per-partition per-region billing, with a 66% average utilization breakeven point versus manual provisioning. The video also dives into data modeling for RU efficiency, including choosing high-cardinality partition keys to minimize cross-partition fan-out, keeping document sizes between 1–10 KB, splitting bounded vs. unbounded data into separate documents, using global secondary indexes for frequent non-partition-key queries, and hierarchical partition keys for storage-heavy or write-heavy IoT scenarios.