Microsoft Silverlight is a discontinued^[5][6]application framework designed for writing and runningrich internet applications, similar toAdobe'sruntime,Adobe Flash. While early versions of Silverlight focused onstreaming media, later versions supportedmultimedia,graphics, and animation, and gave support to developers forCLI languages anddevelopment tools. Silverlight was one of the two application development platforms forWindows Phone, but web pages using Silverlight did not run on the Windows Phone orWindows Mobile versions ofInternet Explorer, as there was no Silverlight plugin for Internet Explorer on those platforms.^[7]

Microsoft Silverlight

Developer(s)	Microsoft Corporation
Initial release	September 5, 2007; 17 years ago (2007-09-05)
Final release	5.1.50918.0[1] (January 15, 2019; 6 years ago (2019-01-15))[±]
Preview release	None[±]
Operating system	Microsoft Windows,macOS, andSymbian OS[2][3]
Platform	IA-32 andx86-64[4]
Type	Application framework,run-time environment andmultimedia framework
License	Freeware
Website	microsoft.com/silverlight

Microsoft terminated support for Silverlight onInternet Explorer 11 (the last remaining web browser still supporting Silverlight) on October 12, 2021.

From the initial launch in 2007, reviewers compared the product to (since discontinued) Adobe's Flash.^[8][9]

According to statowl.com, Microsoft Silverlight had a penetration of 64.2% in May 2011. Usage in July 2010 was 53.6%, whereas as of May 2011^[update] market leader Adobe Flash was installed on 95.3% of browsers, and Java was supported on 76.5% of browsers.^[10] Support of these plugins is not mutually exclusive; one system can support all three.

Silverlight was used to provide video streaming for theNBC coverage of the2008 Summer Olympics in Beijing,^[11] the2010 Winter Olympics in Vancouver,^[12] and the 2008 conventions for both major United States political parties.^[13] Silverlight was also used byAmazon Video andNetflix for their instant video streaming services,^[14][15] but Netflix said in its Tech Blog in 2013 that, since Microsoft had announced Silverlight'send-of-life, they would be moving toHTML video.^[16]

Industry observers announced the death of Silverlight as early as 2011.^[17] In 2012, Microsoft deprecated Silverlight forHTML5 inWindows 8,^[18] but until 2015 it was not clear what Microsoft's official position was on Silverlight's future.^[19] In July 2015, a Microsoft blog post clarified that, "… we encourage companies that are using Silverlight for media to begin the transition to DASH/MSE/CENC/EME based designs".^[6]

Microsoft planned to terminate Silverlight support on October 12, 2021.^[20] Support for IE7–8 was removed between 2014 and 2016, depending on theOS.^[21] Support for IE9 and IE10 has also ended^[21] "or though [sic] the support lifecycle of the underlying browsers,^[22] whichever is shorter."^[20] There is no Silverlight plugin available forMicrosoft Edge [Legacy] or newer.^[6][21] It has not been supported byGoogle Chrome since September 2015^[21][23] or byFirefox since March 2017.^[24]

Since late 2023^[update], less than 0.02% of sites used Silverlight,^[25] less than 1.3% used the also discontinued Adobe Flash Player,^[26] and less than 0.03% use Java client-side (while less than 4.7% use Java server-side).^[27][28]

Silverlight provides aretained mode graphics system similar toWindows Presentation Foundation (WPF), and integratesmultimedia,graphics, animations, andinteractivity into a single run-time environment. In Silverlight applications, user interfaces are declared inExtensible Application Markup Language (XAML) and programmed using a subset of the.NET Framework. XAML can be used formarking up thevector graphics and animations. Silverlight can also be used to createWindows Sidebargadgets forWindows Vista.^[29]

Silverlight supportsH.264 video,^[30]Advanced Audio Coding,Windows Media Video (WMV),Windows Media Audio (WMA), andMPEG Layer III (MP3) media content^[31] across all supported browsers without requiringWindows Media Player, theWindows Media PlayerActiveX control, orWindows Media browser plug-ins. BecauseWindows Media Video 9 is an implementation of theSociety of Motion Picture and Television Engineers (SMPTE)VC-1 standard, Silverlight also supports VC-1 video. According to theend user license agreement VC-1 and H.264 are only licensed for the "personal and non-commercial use of a consumer".^[32] Silverlight makes it possible to dynamically loadExtensible Markup Language (XML) content that can be manipulated through aDocument Object Model (DOM) interface, a technique that is consistent with conventionalAjax techniques. Silverlight exposes aDownloader object which can be used to download content, like scripts, media assets, or other data, as may be required by the application.^[33] With version 2, the programming logic can be written in any.NETlanguage, including some nuclear evolution of commondynamic programming languages likeIronRuby andIronPython.^[34]

Afree software implementation (now abandoned)^[35] namedMoonlight, developed byNovell in cooperation with Microsoft, was released to bring Silverlight version 1 and 2 functionality toLinux,FreeBSD, and other open source platforms, although some Linux distributions did not include it, citing redistribution andpatent concerns.^[36] However, in May 2012, Moonlight was abandoned because of its lack of popularity.^[37]

Over the course of about five years,Microsoft had released five versions with varying platform support: the first version was released in 2007, and the fifth (and final) major version on May 8, 2012. It is compatible with later versions of Internet Explorer web browser on Microsoft Windows (exceptWindows RT)operating systems,^[38] withSafari on ApplemacOS, and with mobile devices using theWindows Mobile^[39] andSymbian (Series 60)^[40] platforms.

Cross-platform Mozilla Firefox support for Silverlight was removed in Firefox 52 released in March 2017 when Mozilla removed support forNPAPI plugins,^[41][42] bringing it in-line with the removal of NPAPI plugin support in Google Chrome.^[43][44]

Silverlight requires anx86 processor withStreaming SIMD Extensions (SSE) support. Supported processors include theIntelPentium III and up, theAMDAthlon XP and up, and newer AMDDurons.

The following table presents an availability and compatibility matrix of Silverlight versions for various operating systems and web browsers.

Support forOpera had been promised since May 3, 2007, when David Storey, the Chief Web Opener at Opera, revealed a Microsoft poster forMIX conference that had shown Opera integration as a part of Silverlight 1.1.^[52] However, Opera was never officially supported by Silverlight.

On Linux and FreeBSD, the functionality was available viaMoonlight andPipelight,^[53][54] though both projects have since been discontinued. Moonlight is available for the majorLinux distributions, with support forFirefox,Konqueror, and Opera browsers, provided it was obtained through Novell.^[55]Miguel de Icaza has expressed an interest in working with developers from other operating systems (BSD, Solaris) and other browsers (Konqueror, WebKit and Opera) to ensure that Moonlight works fine on their systems.^[56] Availability of Moonlight version 1.0 for FreeBSD was announced in March 2009,^[57] but has since been reported not to actually work.^[58]As of 2011^[update], the current version of Moonlight (4 Preview 1) does not officially work on new versions of Firefox (newer than 3.x) on Linux-based operating systems. However, it can be installed in an unofficial way (for example using theAdd-on Compatibility ReporterArchived May 1, 2012, at theWayback Machine add-on) and with Firefox 11 it works correctly when installed. As noted above, the Moonlight project was abandoned in May 2012.

A browser plugin namedPipelight used to provide Silverlight access. Pipelight requires browser support for NPAPI plugins, which newer versions of Firefox, Chrome, and Opera have dropped. As of 2018, the Pipelight project has been discontinued.^[59]

Silverlight was not available onAndroid oriOS, the most prevalent operating systems on themobile market.

Silverlight was the primary development environment forWindows Phone (that is by now discontinued) and is based on Silverlight 4. For previous versions of Windows Mobile, the firstCommunity Technology Preview (CTP) forWindows Mobile 6 was expected in the second quarter of 2008, but it still has not been officially announced. Microsoft has stopped focusing on bringing Silverlight to Windows Mobile 6.x.^[60]Nokia announced plans to make Silverlight for Mobile available forS60 onSymbian OS, as well as forSeries 40 devices and Nokia internet tablets^[61][62] (while it later sold the business to Microsoft and now sells Android tablets and will sellAlcatel-Lucent branded smartphones). Silverlight for Mobile supports Silverlight 2 content and .NET languages.^[39] Silverlight forWindows Phone 7.5 is based on Silverlight 4.^[63]

Silverlight applications could be written in any .NET programming language. As such, anydevelopment tools which can be used with .NET languages can work with Silverlight, provided they can target the Silverlight CoreCLR for hosting the application, instead of the .NET Framework CLR. Microsoft has positionedMicrosoft Expression Blend as a companion tool to Visual Studio for the design of Silverlight User Interface applications.Visual Studio can be used to develop and debug Silverlight applications. To create Silverlight projects and let the compiler target CoreCLR, Visual Studio requires theSilverlight Tools for Visual Studio.^[64]

A Silverlight control is a ZIP format file with extension .XAP containing a list of one or more .NET managed assemblies (.DLL files) along with the AppManifest.XAML file containing this list along with the entry point (class and assembly). It can be hosted in any HTML file using an object tag, for example:

<objectdata="data:application/x-silverlight-2,"type="application/x-silverlight-2"width="100%"height="100%"><paramname="source"value="MySilverLightControl.xap"/></object>

A Silverlight project contains theSilverlight.js andCreateSilverlight.js files which initializes the Silverlight plug-in for use in HTML pages, a XAML file for the UI, and code-behind files for the application code. Silverlight applications are debugged in a manner similar to ASP.NET applications. Visual Studio'sCLR Remote Cross Platform Debugging feature can be used to debug Silverlight applications running on a different platform as well.^[65]

In conjunction with the release of Silverlight 2,Eclipse was added as a development tool option.^[66]

An April 2007PC World report, suggested that Microsoft intended to release certain parts of Silverlight source code asopen source software,^[67] but a week later Sam Ramji, director of platform technology strategy at Microsoft, contradicted the rumors by confirming that the company had no plans to open Silverlight.^[68] Some controls that ship with Silverlight are available under theMicrosoft Public License as a part of a separate project known as theSilverlight Toolkit.^[69]

At introduction, Silverlight'sproprietary nature was a concern to competition due to its potential harm to the open nature of theWorld Wide Web. Advocates offree software were also concerned Silverlight could be another example of Microsoft'sembrace, extend, and extinguish strategy.^[70] Both Microsoft Silverlight and Adobe Flash are proprietary.^[71] Flash's file formats are publicly documented standards,^[72][73] as are Silverlight's.^[74][75] Silverlight, like other web technologies, usespatent-encumbered audio and videocodecs.

TheMono Team abandoned development ofMoonlight, afree andopen-source implementation of both the Silverlight 1 and 2runtimes.^[76] Development was discontinued in 2012 due to the poor acceptance of Silverlight and the restrictions imposed byMicrosoft.^[77]

The project had been officially supported by Microsoft which,^[53] under an agreement withNovell, made not-publicly-available additional specifications, access to the SilverlightBase Class Library APIs, binary codecs and test cases available to the Mono team.^[54][78]

The "covenant" under which Novell was granted this exclusive access also specified conditions incompatible with thelicensing that covers mostfree and open source software. As examples, it specifically required that the software must have been "obtained directly from Novell or through an Intermediate Recipient" and that it must be "not licensed underGPLv3 or a Similar License".^[55] Some free software proponents criticized the covenant.^[79]

Silverlight was criticized for not living up to its cross-platformoperating system compatibility promises, especially on Linux systems, compared to its extensive support on Apple and Microsoft desktops for Internet Explorer, Firefox, and Chrome. Although Microsoft was officially collaborating on the Moonlight project,Bruce Chizen, CEO ofAdobe Systems, which sells the competing proprietary Flash platform, questioned "the commitment of Microsoft to keep the Silverlight platform compatible with other OS besidesWindows".^[80] His concerns are based on "examples from history" where he said that Microsoft had launched products with promises of ongoing cross-platform compatibility that no longer apply, for exampleInternet Explorer for UNIX andWindows Media Player for Mac.

In 2007, California and several other U.S. states asked a district judge to extend most of Microsoft'santitrust case settlement for another five years,^[81] citing "a number of concerns, including the fear that Microsoft could use thenext version of Windows to 'tilt the playing field' toward Silverlight, its newAdobe Flash competitor," says aSeattle Post-Intelligencer article. The final judgment on the motion extended the settlement two years, to November 2009, but for reasons unrelated to Silverlight.^[82]

• Silverlight 1 – Silverlight 1, developed under the codenameWindows Presentation Foundation/Everywhere (WPF/E^[83][84]) was released in 2007. It consisted of the core presentation framework, which is responsible for theuser interface (UI), interactivity and user input, basic UI controls, graphics and animation, media playback,Digital rights management (DRM), andDOM integration.
• Silverlight 2 – Included a version of the.NET Framework and implemented the same fullCommon Language Runtime (CLR) version as .NET Framework 3.0, so it can execute programs written in any .NET language.
• Silverlight 3 – Silverlight 3 was announced on September 12, 2008, and unveiled atMIX09 inLas Vegas on March 18, 2009.^[85] A beta version was made available for download the same day. The final version was released July 9, 2009. Silverlight 3 included more controls^[86]—includingDataGrid,TreeView, various layout panels,DataForm for forms-driven applications andDataPager for viewing paginated data.
• Silverlight 4 – On November 18, 2009, at theProfessional Developers Conference in Los Angeles, Microsoft Corporation unveiled aBeta version of Silverlight 4.^[87] The final version was released on April 15, 2010 (along withSilverlight 4 tools for developers). New features in Silverlight 4 include: support forGoogle's Chrome browser, webcam and microphone, printing, more mouse support, new notification support to send messages to users, new and enhanced controls (e.g., RichTextBox, DataGrid), theming of controls, rendering HTML, better localization, etc.
• Silverlight 5 – The final version was made available to download on December 9, 2011.^[88] New features included GPU-accelerated video decoding, 3D graphics, playback speed controls, remote control, and 64-bit support.^[88]

• Adobe Flash
• Adobe Flash Player
• Adobe AIR
• Microsoft XNA
• XAML Browser Applications (XBAP)
• Java applet
• OpenSilver

• Official website
• Silverlight Developers Center onMSDN
• What's new in Silverlight 5Archived November 12, 2020, at theWayback Machine – step by step in Silverlight 5, many demos and samples available