Windows 7 is a major release of the Windows NT operating system developed by Microsoft. It was released to manufacturing on July 22, 2009, and became generally available on October 22, 2009.[9] It is the successor to Windows Vista, released nearly three years earlier. It remained an operating system for use on personal computers, including home and business desktops, laptops, tablet PCs and media center PCs, and itself was replaced in November 2012 by Windows 8, the name spanning more than three years of the product.

Until April 9, 2013, Windows 7 original release includes updates and technical support, after which installation of Service Pack 1 is required for users to receive support and updates. Windows 7's server counterpart, Windows Server 2008 R2, was released at the same time. The last supported version of Windows based on this operating system was released on July 1, 2011, entitled Windows Embedded POSReady 7.[10][11][12] Extended support ended on January 14, 2020, over ten years after the release of Windows 7, after which the operating system ceased receiving further support. A support program is currently available for enterprises, providing security updates for Windows 7 for up to four years since the official end of life.[13] However, Windows Embedded POSReady 7, the last Windows 7 variant, continued to receive security updates until October 2021.

Windows 7 was intended to be an incremental upgrade to Microsoft Windows, addressing Windows Vista's poor critical reception while maintaining hardware and software compatibility. Windows 7 continued improvements on Windows Aero user interface with the addition of a redesigned taskbar that allows pinned applications, and new window management features. Other new features were added to the operating system, including libraries, the new file-sharing system HomeGroup, and support for multitouch input. A new "Action Center" was also added to provide an overview of system security and maintenance information, and tweaks were made to the User Account Control system to make it less intrusive. Windows 7 also shipped with updated versions of several stock applications, including Internet Explorer 8, Windows Media Player, and Windows Media Center.

Unlike Vista, Windows 7 received critical acclaim, with critics considering the operating system to be a major improvement over its predecessor because of its improved performance, its more intuitive interface, fewer User Account Control popups, and other improvements made across the platform. Windows 7 was a major success for Microsoft; even before its official release, pre-order sales for the operating system on the online retailer Amazon.com had surpassed previous records. In just six months, over 100 million copies had been sold worldwide, increasing to over 630 million licenses by July 2012. By January 2018, Windows 10 surpassed Windows 7 as the most popular version of Windows worldwide.[14] As of December 2021, 12.76% of traditional PCs running Windows are running Windows 7.[15] It still remains popular in countries such as Syria, China, India, and Venezuela.[16][17][18]

Windows 7 is the final version of Windows which supports processors without SSE2 or NX (although an update released in 2018 dropped support for non-SSE2 processors). Its successor, Windows 8, requires a processor with SSE2 and NX in any supported architecture.