Open Settings
Go to System
Click Storage
Review the storage breakdown by category
Click each category to see what is using space
Open File Explorer
Check Downloads, Desktop, Documents, Pictures, Videos, and Music
Sort folders by size
Right-click a drive in This PC
Select Properties
Check used and free space
Use Disk Cleanup
Open Task Manager
Check installed apps in Settings > Apps
Uninstall large unused programs
Search for large files in File Explorer
Use a storage analysis tool if needed