Windows Internet Explorer (formerly Microsoft Internet Explorer abbreviated MSIE), commonly abbreviated to IE, is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems starting in 1995. It has been the most widely used web browser since 1999, attaining a peak of about 95% usage share during 2002 and 2003 with IE5 and 6 but steadily declining since, despite the introduction of IE7. Microsoft spent over 100 million dollars (USD) a year in the late 1990s, with over 1000 people working on IE by 1999.
Internet Explorer was first released as part of the add-on package Plus! for Windows 95 in 1995. Later versions were available as free downloads, or in service packs, and included in the OEM service releases of Windows 95 and later versions of Windows. The most recent release is version 7.0, which is available as a free update for Windows XP Service Pack 2, and Windows Server 2003 with Service Pack 1 or later, Windows Vista, and Windows Server 2008. Internet Explorer 8 is under development and is expected to be released by the end of 2008.
Other versions available since the late 1990s include an embedded OEM version called Internet Explorer for Windows CE (IE CE) available for WinCE based platforms and is currently based on IE6. Internet Explorer for Pocket PC, later rebranded Internet Explorer Mobile for Windows Mobile was also developed, and remain in development alongside the more advanced desktop versions.
Internet Explorer 8 is the latest version of Internet Explorer and has been in development since August 2007 at the latest. On March 5, 2008, the first public beta (Beta 1) was released to the general public. On August 27, 2008, the second public beta (Beta 2) was released. It supports Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista and Windows Server 2008 on both 32-bit as well as 64-bit architectures.
Security, ease of use, and improvements in RSS, CSS, and Ajax support are Microsoft's priorities for IE8. It includes much stricter compliance with web standards, including a planned full Cascading Style Sheets 2.1 compliance for the release version. All these changes allow Internet Explorer 8 to pass the Acid2 test. However, to prevent compatibility issues, IE8 also includes the IE7 rendering behavior. Sites that expect IE7 quirks can disable the IE8's breaking changes by including a meta element.
IE8 also includes numerous improvements to JavaScript support as well as performance improvements. It includes support for Accelerators - which allow supported web applications to be invoked without explicitly navigating to them - and WebSlices - which allows portions of page to be subscribed to and monitored from a redesigned Favorites Bar. Other features include InPrivate privacy features, and SmartScreen phishing filter.