Microsoft , alongside a free upgrade option for Windows 7 and 8.1 users.
On July 29, you can get Windows 10 for PCs and tablets by taking advantage of the free upgrade offer, or on a new Windows 10 PC from your favorite retailer. If you purchase a new Windows 8.1 device between now and then, the Windows 10 upgrade will be available to you and many retail stores will upgrade your new device for you.
Windows 10 brings a true personal assistant in Cortana, a totally new browser called Microsoft Edge, and Universal Office apps, including a universal Xbox app. Windows Continuum allows devices to transform from one form factor to the other, enabling smooth transitions of your tablet into a PC and back, and even allows your Windows 10 phone to work like a PC.
Although there's not a whole lot known about Windows Hello, (it is still disabled in the latest Insider builds) Microsoft says that the app:
..greets you by name and with a smile, letting you log in without a password and providing instant, more secure access to your Windows 10 devices. With Windows Hello, biometric authentication is easy with your face, iris, or finger, providing instant recognition.
Microsoft has also published a video introducing Windows 10 which you can view above, although most readers will already be familiar with it from the Insider Preview program, it's fair to say that many more people will start to become aware of it from today due to the reservation app.
And finally, for those wondering "Windows 10 brings back the Start menu you know and love." Isn't this reason enough to upgrade from Windows 7, we wonder?