Windows
In plain terms
Microsoft's dominant desktop operating system.
Going deeper
Windows is the most widely-used desktop OS, known for its GUI, broad software and hardware support, and enterprise integration. It rules consumer desktops.
Under the hood
NT kernel underpins modern versions; strong backward compatibility and Active Directory in enterprises.
Examples
Desktop computing, enterprise, gaming, Office, Active Directory.
Think of it like...
Like the most common storefront that the majority of desktop users walk into.