Windows 7,8,8.1

windows 7 Is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops, netbooks, tablet PCs. It was released to manufacturing on July 22, 2009.
The taskbar has seen the biggest visual changes, where the old Quick Launch toolbar has been replaced with the ability to pin applications to taskbar. Buttons for pinned applications are integrated with the task buttons. These buttons also enable Jump Lists to allow easy access to common tasks. To the far right of the system clock is a small rectangular button that serves as the Show desktop icon. This button is part of the new feature in Windows 7 called Aero Peek. Hovering over this button makes all visible windows transparent for a quick look at the desktop.
windows 8 has seen several developments in the graphical interface and functional properties of the system alike.
Windows 8.1 (formerly it was called Blue) is a free update for Windows 8, which was officially launched on October 17, 2013, this update will restore the Start button famous on the desktop of Windows, in addition to the new features browser Internet Explorer 11 apps installed new, the user will note that himself if you upgrade to the new version (8.1).
You don t have to reinstall your desktop applications or your Windows Store apps, and all your files are still there (as are libraries and the icons pinned to your taskbar.