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. Among Windows 7's new features are advances in touch and handwriting recognition, support for virtual hard disks, improved performance on multi-core processors, improved boot performance, Direct Access, and kernel improvements. Windows 7 adds support for systems using multiple heterogeneous graphics cards from different vendors, a new version of Windows Media Center, a Gadget for Windows Media Center, improved media features. 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 It has seen several developments in the graphical interface and functional properties of the system alike. 1. work all of the programs that were run on Windows 7 without any problems. 2. Add a new property "reset device and revive" the advantage of simplicity and convenience to replace restore order. 3. Alerts system update will appear in the bottom right of the screen. 4. System management tasks updated end applications that run in the background. 5. Multi-monitor support allows the possibility of a background and one of the two screens as well as the taskbar for each screen separately. 6. Improving property zoom. 7. Feature writing on a keyboard with two fingers Optionally available. 8. The possibility of synchronization between all devices and Windows 8, which is owned by the user. 9. Updated interface log on to support in addition to the password and PIN system by clicking on the custom image. 10. System will include a built-in anti viruses. 11. Some of the limitations will stay themselves like(CTRL+C ,CTRL+V , CTRL+Z). windows 8.1 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.