Your Windows PC is doing something you probably didn't know about. While you browse, work, or game, it's quietly uploading pieces of Windows Update files to other computers around the world. This isn't a bug or malware, it's a feature called Delivery Optimization that Microsoft enables by default.
Delivery Optimization is designed to make Windows updates faster by letting PCs share update files with each other instead of everyone downloading from Microsoft's servers. Your PC downloads parts of updates from other computers that already have them, and in return, your PC uploads those same files to others who need them.
