Built into SQL Server are a growing set of exceptionally useful system views and tables that provide insight into many server and database components.

This demo-heavy session provides a wide array of queries and tools that can leverage system data to understand how different systems work, including:
Wait stats
Windows/System info
Performance counters
Index/Columnstore index structure
Registry entries
Database files, size, and metadata
Query stats
...and more!

Using these tools, database maintenance can be better automated and validated and application and analytics code can make smarter use of system metadata when making important processing decisions.

These are my favorite applications of system data for you to enjoy!