The day has arrived. Windows 10, Microsoft's latest operating system and the follow-up to the controversial Windows 8 (there was no Windows 9), launched on Wednesday--and you can probably get it for free.

Windows 8, released in October 2012, was controversial in part because of its touch-focused tile design that was dramatically different to Windows 7. Microsoft addressed these criticisms with frequent--and substantial updates--including Windows 8.1. The company isn't starting over with Windows 10, but Microsoft appears to be taking a more measured approach with its latest OS.