About MS SQL Server
The enterprise database most .NET applications sit on.
Microsoft SQL Server is the enterprise relational database behind a very large share of .NET applications, Dynamics 365 deployments and internal systems built inside Microsoft-first organisations. It runs on-prem and on Azure, and usually holds the operational data that matters most to the business: orders, transactions, schedules, customer records.
The point of pulling SQL Server into a warehouse is that reports written directly against the production database age badly. Schemas drift with every release, big joins compete with live traffic, and the ETL someone built five years ago has become the thing that no one wants to touch. In a warehouse, SQL Server joins Dynamics 365, Business Central, Shopify and the accounting ledger without putting reporting load on the system that has to stay up.