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Comparing Flash and Silverlight

written by: John Lister•edited by: Brian Nelson•updated: 12/22/2008

Silverlight is Microsoft's challenger to Adobe's Flash as the leading system for multimedia content built-in to web pages. We explore the differences and similarities between the two systems.

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    What are Flash and Silverlight?

    Flash is an Adobe product, introduced in 1996, which is classed as multimedia platform. It’s most commonly known for its use in animations on webpages, particularly those which allow the user to interact with the animation, for example clicking on one of a selection of options.

    Technically Flash content can be created as a standalone file which users view with a dedicated program. However, it’s usually used by being embedded in a web page and played automatically by a plug-in for the browser.

    Silverlight, which debuted in 2007 is Microsoft’s take on the multimedia plug-in. It’s main selling point is that it allows Windows Media format audio and video content to play on machines which don’t have Windows Media Player installed. As Silverlight is a much smaller download, it may be appealing to website visitors who wouldn’t bother downloading Windows Media Player just to watch a particular clip.

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    What operating systems do they work on?

    The Flash Player is available for virtually every operating system, though the only 64-bit edition is an experimental version for Linux.

    Silverlight has official Windows and Mac versions, with some mobile phone systems also supported. There is a Linux equivalent named Moonlight which is produced with Microsoft’s permission but only under strict conditions.

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    How many people use each system?

    Adobe’s most recent figures claim 98.6% of users in ‘mature markets’ (the United States Canada, United Kingom, France, Germany and Japan) have some form of the Adobe Player plug-in installed, with 89.4% having the latest version. In ‘emerging markets’ the figures are 97.3% and 82.4% respectively.

    According to, 13.87% of users have Silverlight installed on their computers.

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    Which well-known sites use it?

    While many sites contain Flash content, perhaps the biggest is YouTube. Videos shown on the site are in Flash Video (FLV) format.

    The most notable site to use Silverlight content (apart from Microsoft itself) was NBC, which made it a mandatory installation for visitors who wanted to watch its streaming coverage of the 2008 Summer Olympics. This raised some questions about whether Microsoft was acting anti-competitively in promoting its Silverlight player.

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    Both Adobe and Microsoft have their own software for producing Flash/Silverlight content. (Any program using the .NET programming language can create Silverlight content.) There are also many third-party packages for Flash, but Microsoft has not licensed any independent software for Silverlight production.

    Many common effects can easily be produced in both systems. has examples of the relevant code for a variety of effects in each of the two systems.

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    Legal issues

    The NBC deal raised some questions about whether Microsoft was acting anti-competitively in promoting its Silverlight player. There’s also been some concern about a deal under which HP will set Microsoft’s search engine as the default on its machines; the relevant toolbar uses Silverlight, meaning it will automatically be installed on the HP computers.

    Seven states (plus the District of Colombia) have files cases asking that Microsoft be restricted from giving undue favour to Silverlight in Windows 7.

    However, there is a strong argument that Flash is already so well-established that Silverlight’s success can’t cause it any serious harm. That argument says that with a ready-made audience of virtually all internet users for Flash developers, people will generally only produce Silverlight content where they feel the format is superior: that should force Microsoft to compete on quality rather than through existing market strength.