What is Microsoft Silverlight?
Microsoft Silverlight is a cross-browser, cross-platform plug-in for delivering the next generation of Microsoft .NET–based media experiences and rich interactive applications for the Web.
Is Silverlight free?
Yes, Microsoft has made the Silverlight browser plug-in freely available for all supported platforms and browsers.
Yes. Microsoft Silverlight was formerly code-named "WPF/E."
What is the long-term goal or vision for Silverlight?
Silverlight is a cross-browser, cross-platform plug-in for delivering the next generation of .NET-based media experiences and rich interactive applications (RIAs) for the Web. Silverlight offers a flexible programming model that supports AJAX, Microsoft Visual Basic .NET, C#, Python, and Ruby and integrates with existing Web applications. Silverlight media capabilities include fast, cost-effective delivery of high-quality audio and video to all major browsers including Mozilla Firefox, Apple Safari, and Windows Internet Explorer running on Mac OS or Microsoft Windows. By using Microsoft Expression Studio and Microsoft Visual Studio, designers and developers can collaborate more effectively using the skills they have today to light up the Web of tomorrow.
Who is the target audience for Silverlight?
Microsoft Silverlight ushers in a new era of rich media experiences and rich interactive applications for the Web.
For Business Decision Makers, take your existing infrastructure to another level by deploying the lowest TCO solution for rich web experiences today and harnessing the full power of the Microsoft application platform including IIS, Windows Media Services, and SQL Server. Take advantage of role-specific productivity tools such as Visual Studio and Expression Studio to bring high-fidelity experiences into your enterprise applications.
For Content Owners, using Silverlight, you can light up the Web with high fidelity video, animation, and vector graphics efficiently and cost effectively using the Emmy® Award winning Windows Media platform and industry standard WMV9 (SMPTE VC-1).
For Designers and Developers, quickly develop Silverlight content using familiar, role-specific tools like Visual Studio and Expression Studio that facilitate developer and designer collaboration. Because Silverlight supports XAML, JavaScript, and .NET programming, you can use the skills you have today to develop the applications of tomorrow.
What are the main features and benefits of Silverlight?
Compelling Cross-Platform User Experiences
Deliver media experiences and rich interactive applications for the Web that incorporate video, animation, interactivity, and stunning user interfaces.
Seamless, fast installation for users, thanks to a small, on-demand, easy-to-install plug-in that is under 2 megabytes (MB) in size and works with all leading browsers.
Consistent experiences between Windows-based and Macintosh computers without any additional installation requirements.
Create richer, more compelling Web experiences that take greater advantage of the client for increased performance.
Stunning vector-based graphics, media, text, animation, and overlays that enable seamless integration of graphics and effects into any existing Web application.
Enhance existing standards/AJAX-based applications with richer graphics and media, and improve their performance and capabilities by using Silverlight.
Flexible Programming Model with Collaboration Tools
Based on the Microsoft .NET Framework, Silverlight enables developers and designers to easily use existing skills and tools to deliver media experiences and rich interactive applications for the Web.
Simple integration with existing Web technologies and assets means Silverlight works with any back-end Web environment or technology. No "rip and replace" required. Silverlight integrates with your existing infrastructure and applications, including Apache, PHP, as well as JavaScript and XHTML on the client.
Choice of development languages including JavaScript, Ruby, Python, C#, Visual Basic .NET, and more.
Role-specific tools for both designers and developers that take advantage of Web standards and the breadth of the Microsoft .NET–connected software features.
For designers: Microsoft Expression Studio for creating interactive user interfaces and media rich experiences, preparing media for encoding and distribution, and creating World Wide Web Consortium (W3C) standards-compliant sites using modern XHTML, XML, XSLT, CSS, and ASP.NET.
For developers: Microsoft Visual Studio for developing client and server code with full Microsoft IntelliSense, powerful cross-platform debugging, rich language support, and more.
Consistent presentation model by using XAML, the declarative presentation language used in Windows Vista–based applications. Controls, visual designs, media, and other elements can be presented with full design fidelity in both Silverlight and Windows–based applications.
Extensible control model makes it easy to add rich content and behaviors while enabling efficient code-reuse and sharing.
Dramatically improved performance for AJAX–enabled Web sites with the power, performance, and flexibility of Silverlight and .NET-connected software.
High Quality, Low Cost Media
Unified media format that scales from high definition (HD) to mobile with Windows Media Video (WMV), the Microsoft implementation of the Society of Motion Picture and Television Engineers (SMPTE) VC-1 video standard, as well as support for Windows Media Audio (WMA) and MP3 audio.
Add vector-based graphics and overlays to media with support for integration of graphics that scale to any size and broadcast-style overlays for tickers and closed captioning.
Flexible ad-insertion solutions with video and animation, including the ability to deliver fluid, broadcast-style video or animated advertisements without loss of visual fidelity or motion quality.
Lower-cost media streaming with Emmy Award–winning Windows Media technologies that can lower the cost of streaming delivery by up to 46%, and enjoy the flexibility to work with your existing Windows Media streaming deployments. Even further cost reductions are possible with the upcoming Microsoft Internet Information Services (IIS) Media Pack for Microsoft Windows Server 2008.
Broad ecosystem of media tools, servers, and solutions compatible with the Windows Media operating system.
Microsoft PlayReady content-access technology that delivers a single solution for digital rights management support on both Windows-based and Macintosh computers for content providers (coming in Silverlight 1.1)
Powerful encoding tools for live and on-demand publishing of media experiences with Microsoft Expression Encoder, including hardware-accelerated encoding of WMV and VC-1 at up to 15 times the performance of software alone when paired with a Tarari Encoder Accelerator board.
Connected to Data, Servers, and Services
Easily mash-up and incorporate services and data from anywhere on the Web by taking advantage of the Silverlight support for LINQ and LINQ-to-XML while accessing that data with common protocols like JSON, RSS, POX, and REST.
Increase discoverability of rich interactive application (RIA) content that can be indexed and searched due to the text-based XAML format that describes interface and content in a Silverlight-based application.
Rapidly scale applications with Silverlight Streaming by Windows Live to host and integrate software services and media content.
What is new in Silverlight 1.0 Release to Web (RTW) since Silverlight 1.0 Release Candidate (RC)?
Silverlight 1.0 Release Candidate (RC) offered additional features that were added since the Silverlight 1.0 beta, such as new media APIs, improved performance, better serviceability, and bug fixes. Silverlight 1.0 RC also included a Go-Live license. Silverlight 1.0 Release To Web (RTW) is the final release of Silverlight 1.0. It includes bug fixes based on RC that we received from customers.
What is the significance of the Silverlight 1.0 Release To Web (RTW)?
Silverlight 1.0 Release To Web (RTW) is the final release of the product.
When can we expect a refresh to the Silverlight 1.1 bits?
The Silverlight 1.0 RTW is accompanied by a refresh of the Silverlight 1.1 Alpha bits called Silverlight 1.1 Alpha September Preview that is compatible with Silverlight 1.0 RTW.
Will my Silverlight 1.0 applications be compatible when 1.1 comes out?
Yes.
Which platforms and browsers will Silverlight support?
Silverlight will support all major browsers on both Mac OS X and on Windows. Particular care is being taken to account for differences in platform and browser capabilities to ensure a consistent experience including experiences on Firefox, Safari, and Internet Explorer. Microsoft will extend the support for Silverlight on Linux through a partnership with Novell.
Silverlight 1.0 will support the following platforms and browser configurations:
OS*/Browser
Internet Explorer 6 SP2
Internet Explorer 7.0
FireFox 1.5.x.x
FireFox 2.0
Mac Safari 2.0.4
Windows XP Gold/SP1/SP2
Supported
Supported
Supported
Supported
Not Applicable
Windows Vista
Not Applicable
Supported
Supported
Supported
Not Applicable
Windows 2000
Not Supported; Planned
Not Supported; Planned
Not Supported; Planned
Not Supported; Planned
Not Applicable
Mac OS 10.4.8 PPC
Not Applicable
Not Applicable
Not Supported; Planned
Not Supported; Planned
Supported
Mac OS 10.4.8 Intel
Not Applicable
Not Applicable
Supported
Not Supported; Planned
Supported
*Novell will deliver an implementation of Silverlight on Linux, called Moonlight.
How will Silverlight be distributed by Microsoft?
Microsoft designed Silverlight to fit a broad range of uses that require reach and a compelling user experience. Many Microsoft projects will be using Silverlight for delivering richer user experiences and applications for the Web.
Will I need more memory, a faster processor, or a better Graphics Processing Unit (GPU)?
Microsoft designed Silverlight with the ability to deliver high-fidelity experiences on the broadest set of system configurations. Some features, such as HD video, may benefit from newer personal computers. Final system requirements will be available at release.
Is Microsoft considering support for additional operating systems?
Microsoft is gathering feedback from customers like you on Silverlight and to help determine which platforms should be supported in the future.
Which devices will be supported?
Device platforms are being considered based on customer feedback.
How do I verify Silverlight is installed?
Verify your installation by visiting the Silverlight Test Site.
Development related
Can I redistribute the Silverlight 1.1 Alpha September preview release?
No, Silverlight 1.1 Alpha September preview does not offer a Go-Live license at this time.
What is new in Expression Encoder Release To Web since its preview?
New features in the Expression Encoder RTW release include: support for live encoding from professional camcorders and webcams, a publishing plug-in for delivering finished projects to Silverlight Streaming, source profile support, which lets you add metadata (captions, chapter markers and Silverlight templates) to existing Windows Media content without having to recompress and an add-on pack of eight new Silverlight media player templates.
Does the recently released Visual Studio 2008 Beta 2 and Expression Blend 2 August preview work with Silverlight 1.0 RTW?
Yes. Visual Studio 2008 Beta 2 also offers an updated Community Technology Preview (CTP) of the Silverlight Add-In for Visual Studio 2008. The add-in will enable developers to use Silverlight 1.0 RTW and Silverlight 1.1 Alpha September preview, capture the full power of Visual Studio 2008, and collaborate with designers using Expression Blend 2 September Preview.
Where can I find Silverlight and associated Software Development Kits (SDKs) for download?
Silverlight bits can be found elsewhere on this site. Developer and designer resources such as the SDK and CTP releases can be found at the MSDN Silverlight site. Another great resource for getting started with Silverlight is the newly launched Silverlight community site.
How can I build experiences and applications with Silverlight?
Silverlight development tools include role-specific productivity tools for both designers and developers:
Expression Studio empowers designers to create interactive UI and media-rich experiences, prepare media for encoding and distribution, and create W3C standards-compliant sites using modern XHTML, XML, XSLT, CSS, and ASP.NET. Expression Design includes support for exporting XAML for Silverlight. Expression Blend 2 September Preview is compatible with Silverlight 1.0 RTW and Silverlight 1.1 Alpha September Preview. Expression Encoder (previously called Expression Media Encoder) enables video professionals to encode, enhance, and publish media assets to the Web.
Visual Studio empowers developers to develop client and server code using full IntelliSense, powerful debugging, rich language support, and more.
By using Expression Studio and Visual Studio, designers and developers can collaborate more effectively using the skills they have today. Additionally, Silverlight supports a consistent subset of XAML for declarative programming, the same format found in Microsoft .NET 3.0 technology namely Windows Presentation Foundation.
Are the features of the Macintosh and Windows releases of Silverlight fully compatible?
Yes.
When would a customer use Silverlight instead of ASP.NET AJAX?
Silverlight integrates with existing Web applications, including ASP.NET AJAX applications. Consequently, ASP.NET AJAX and Silverlight are designed to be complementary technologies. In the broader sense, Silverlight can talk to any AJAX application, both client-side and server-side. ASP.NET AJAX can additionally be used to control Silverlight-based visualization of data or delivery of rich experiences. Examples might include mapping applications or video playback with rich presentation.
ASP.NET AJAX and Silverlight at final release will also benefit its status as a fully supported technology from Microsoft with the benefits of technical support around the clock and the breadth support of the Microsoft development community. AJAX is a fundamental technology supported in Silverlight and now, in ASP.NET.
Customers can enhance existing ASP.NET or ASP.NET AJAX applications by using Silverlight's media experiences and RIAs.
What is the ASP.NET Futures (July 2007) release?
The Microsoft ASP.NET Futures July 2007 release contains an early developer preview of features providing a wide range of new functionality for both ASP.NET and Silverlight. The Futures release includes early experimental versions of features currently under consideration for future versions of ASP.NET and the .NET Framework. The Futures releases assume prior knowledge of the core features of ASP.NET, including the previous ASP.NET AJAX Futures January CTP.
How does Silverlight make the Microsoft development system better?
Silverlight is a cross-browser, cross-platform plug-in for delivering the next generation of media experiences and rich interactive applications (RIAs) for the Web. Examples include:
For ASP.NET-based Web applications, Silverlight provides a rich UI front-end that, with a consistent programming model, adds support for richer interactivity, media, and audio.
For Microsoft SharePoint–based content, Silverlight offers the ability to create rich Web parts.
For Windows Live services, Silverlight offers the ability to consume services and APIs more effectively.
When would a customer use Silverlight instead of Windows Presentation Foundation (WPF)? Is Silverlight more appropriate for certain types of applications?
WPF and Silverlight are complementary platforms, based on XAML for presentation:
WPF provides a unified programming model for building the best Windows Vista era of smart-client user experiences that incorporate UI, 3D, media, and documents.
Silverlight is a cross-browser, cross-platform plug-in for delivering the next generation of media experiences and RIAs for the Web by using a consistent subset of WPF features and the flexibility of AJAX for programmability.
Thus, both WPF and Silverlight enable developers and designers to develop visually stunning user experiences, but they are designed for different scenarios.
What features are missing from Silverlight presentation markup that will be supported in WPF (Windows Presentation Foundation)?
Some high-end Windows-specific features of WPF, such as real 3-D, hardware-based video acceleration, and full document support, will not be supported in Silverlight. This is by design to support Silverlight's cross-browser, cross-platform reach scenario, which demands a light-weight plug-in. However, Silverlight will offer a uniform runtime that can render identical experiences across browsers on both Mac OS and Windows. In addition, because both WPF and Silverlight support XAML, .NET, and role-specific tools namely Visual Studio and Expression Studio, designers and developers will be able to use the same skills and the same tools to build continuum user experiences spanning connected desktop applications for Windows to rich interactive applications/media experiences for the Web.
Where can I go to connect with other Silverlight developers to ask questions?
For Silverlight-related forums, blogs, and community resources for the CTP, visit the Silverlight Support and Community page.
Media (audio and video)
What is the relationship between Silverlight and Windows Media technologies?
Silverlight builds on top of Windows Media in a fashion similar to the Xbox XDK (Xbox Development Kit), enabling developers and designers to collaborate in building media experiences and RIAs. Silverlight is released by the Server and Tools Division at Microsoft as a part of the .NET Framework.
Is Silverlight a new media player?
No. Silverlight is a cross-browser, cross-platform plug-in for delivering media experiences and RIAs. It is not a desktop application or stand-alone media player.
What is the relationship between Silverlight and Windows Media Player?
The Silverlight browser plug-in is a separate component, independent of Windows Media Player. Silverlight is designed for delivery of cross-platform, cross-browser media experiences and rich interactive applications (RIAs) inside a Web browser combining audio, video, animation, overlays, and more. Windows Media Player delivers a breadth of local playback and user focused experiences, while also offering support for application and Web page embedding.
Do I need to have the latest version of Windows Media Player installed?
No. Silverlight is completely independent and when installed is less than 2 MB in size.
What audio or video formats are supported in Silverlight?
Silverlight supports Windows Media Audio and Video (WMA, WMV7–9) and VC-1, as well as MP3 audio. Additional formats may be available over time based on customer feedback.
Will Silverlight support all the codecs Windows Media Player supports?
Since Silverlight is a lightweight cross-platform technology, it only carries the most common codices that are needed for Web playback. However, we are gathering information from customers about the needed codices and can update Silverlight when necessary.
What is SMPTE VC-1?
VC-1 is an industry-standard video format, recognized by the Society of Motion Picture and Television Engineers (SMPTE), and most notably ships in all HD-DVD and Blu-ray Disc–certified electronics, hardware, and tools. Windows Media Video 9 (WMV-9) is the Microsoft implementation of the SMPTE VC-1 standard video codec. Microsoft initiated development of the standard with the release of WMV-9 to SMPTE.
Does Silverlight support HD quality?
Yes, Silverlight supports 720p, HD quality with considerable performance benefits over other solutions. Performance is dependent upon the central processing unit (CPU) capabilities of your computer and configurations. Generally, in testing, a 3-gigahertz (GHz) CPU and/or dual-core support greatly benefit the HD playback experience.
Will Silverlight work with my new or existing Windows Media services platform for streaming?
Yes, in the final release. The CTP supports progressive download and playback from any server. In its final release, Silverlight will take advantage of Windows Server features for streaming.
Will Silverlight support live streaming events as well as downloading media?
Yes, in the final release. The February CTP is optimized for progressive "download and play" scenarios to test the platform.
Does Silverlight support MPEG4 and H.264 video, or Advanced Audio Coding (AAC) audio, or Flash video?
No. However, content from many of these formats can be transposed into formats that are supported by Silverlight, such as by an automated server function (many available third-party solutions support this workflow), and then incorporated into a Silverlight-based application.
Will Silverlight support the full range of APIs offered by the Windows Media Player ActiveX control today?
We are actively speaking to customers and partners about their needs.
Will Silverlight support digital rights management?
For content providers, Silverlight will support digital rights management (DRM) built on the recently announced Microsoft PlayReady content access technology on Windows-based computers and Macintosh computers.
Will Silverlight-based applications run in Media Center? What about Media Center Extender?
Silverlight-based applications can run in Media Center but may have rendering issues on Media Center Extenders. Applications that are implemented using the Media Center SDK will provide a better experience. The engineering team is actively evaluating customer requirements for a variety of scenarios moving forward.
Are there any new tools for creating and publishing media content with Silverlight?
Yes. Expression Encoder, a feature of Expression Media, will support live and on-demand encoding and template-based publishing of Silverlight media experiences. In addition, Silverlight works with the broad range of Windows Media encoding tools and utilities available today. Additional details will be made available shortly.
Server
Will Silverlight-based applications and content run on any Web Server? What are the benefits to running Silverlight on servers running Windows?
Silverlight works with any Web server just like HTML does. Video and audio content can also be progressively downloaded and played back from any Web server platform. Benefits of Windows server-based distribution of Silverlight applications include Windows Media Services with Fast Stream (instant playback) and Fast reconnect technologies, lower distribution costs (streaming users only download what they watch), and tap into the full Windows server ecosystem of platform components and partner solutions. Those benefits will be enhanced in the future version of Windows Server 2008 and with IIS 7.0.
Is Microsoft making new server investments for creation and delivery of digital media?
Windows Server 2008 raises the bar significantly on security, reliability, and robustness, and it is already considered to have excellent live and streaming delivery. New investments are being made in two key areas: IIS 7.0 and Windows Media Services.
Windows Media Services (WMS): Under development for Windows Server 2008 to provide advanced streaming media support, enabling significantly more scalable live and on-demand broadcasts that build on the industry-leading availability, cost-efficiency, and uptime offered by Windows Server 2003 today. Silverlight joins the list of client platforms that can connect to and present WMS streamed audio and video as an integrated part of media-enabled applications for the Web, whether you are building a simple cross-platform, browser-based media experience or a rich interactive application (RIA) for the Web.
IIS 7.0: For customers who prefer to use IIS for progressive download of media-enabled applications and experiences, Microsoft announces the IIS 7.0 Media Pack. The IIS 7.0 Media Pack reduces the cost of delivering downloaded content, such as media, thanks to bit-rate throttling. The IIS 7.0 Media Pack will be a free download for customers of Windows Server 2008 later this year.
Globalization and localization
What UI languages does Silverlight provide?
In the initial release, the installation and control runtime are available in English. Developers may provide an in-page "Get Microsoft Silverlight" experience for their customers in English, French, German, Spanish, Italian, Chinese Simplified, Chinese Traditional, Korean, Japanese, Russian and Brazilian Portuguese. Support for additional languages is planned to follow.
Is Silverlight supported on various locales?
Silverlight installs on localized versions of Macintosh computers and Windows. It can support the development of video and rich Web experiences for a worldwide audience.
Does Silverlight support East Asian languages?
In the initial release, there is support of East Asian languages via static text (Glyph element). Dynamic text (TextBlock element) does not fully support East Asian languages at this time. Developers may utilize the rendering of the browser (DHTML) or text-graphics as alternative approaches.
Does Silverlight support bi-di or complex scripts?
No. In the initial release, Silverlight does not support the bi-directionality, shaping or justification support required by complex script languages. A developer, however, may utilize the rendering of the browser (DHTML) or text-graphics as alternative approaches.
Silverlight streaming service
What is Microsoft Silverlight Streaming by Windows Live?
Microsoft Silverlight Streaming by Windows Live offers a free cloud-based hosting and streaming solution for quickly delivering high-quality, high-scale, cross-platform, cross-browser, media-enabled RIAs.
How much does Silverlight Streaming cost?
While the product is in pre-release, storage and delivery is free up to 4 GB, with outbound streaming up to 700 Kbps. As we move out of Beta, developers/designers will have continued use of the service with up to 1 million minutes of free video streaming at 700 Kpbs per site per month. Unlimited streaming will also be available for free with advertising, or with payment of a nominal fee for the service for use without advertising.
How much is the pay-for-use service if I chose not to use Microsoft-sponsored advertising?
We're not prepared to discuss the final pricing of the nonadvertising-based product at this time except to say that it will be extremely cost competitive. The advertising-based product will continue to be free in perpetuity.
Can this service be used for non-video files such as music files?
Yes. Anything that can be encoded as Silverlight application content and rendered in Silverlight can be used. This includes music files such as WMA and MP3. Business logic written in Microsoft JScript can also be stored and streamed to the client. In the future, you will also be able to use any Silverlight Dynamic Language Runtime assemblies.
How much storage do I get and what is the bit rate?
A user receives 4 GB of free storage for Silverlight Streaming applications. Each media element in a Silverlight Streaming application cannot exceed a 10-minute uninterrupted video stream at 300 kilobit/s. The peak outbound bit rate for Silverlight Streaming is 700 kilobit/s. As the limit is set based on byte size instead of duration, by using the full bandwidth of 700 kilobit/s, the video will be truncated to approximately 4 minutes.
What video encoding formats are supported?
The designer or developer is free to use any encoding format for their video supported by the Windows Media Video codec. This includes Variable Bit Rate (VBR) encoding for DVD-quality video and the use of the VC-1 codec for high-definition content. However, for HD content, be aware that the optimized output rate from the service is 700 kilobit/s, which means the client will not receive real-time delivery of HD video.
What is the difference between Silverlight Streaming and other video sharing services?
Silverlight Streaming is focused on developers who want to build their own media-rich applications or Web sites. Unlike other video sharing services, there are no third-party branding requirements for the use of Silverlight Streaming, and the developer is in full control over their rich media experience within the context of their Web site. This includes items that are not presently supported on other sites such as 16:9 aspect ratio video, DVD-quality video, stereo audio, and customized UI (XAML).
Does Silverlight Streaming replace other video and file sharing services?
This service does not replace other video or file sharing services. Silverlight Streaming is intended to give developers the power and flexibility to build such services themselves, and more.
What steps are being taken to ensure copyrighted content or illegal material is not uploaded?
The media owners as well as the Silverlight developers rendering content in their third-party Web sites are responsible for respecting the copyright of the content they expose. Microsoft reserves the right to remove from our servers any copyrighted content brought to our attention. The front page of our service has a Report Abuse button.
Can I string together longer clips made of 10-minute files in a playlist?
Yes, so long as the total size of your Silverlight application content does not exceed the 4-GB storage limits of this free service.
What scalability does this system deliver? What if I have a large number of visitors to my Web site at the same time?
This service uses the Microsoft content delivery network specifically optimized for long-form video content. It has a provisioned global aggregate data rate in excess of 1 terabit/second.
Does this solution compete with content delivery networks (CDNs)?
No, this service uses the Microsoft CDN for the low latency delivery of media and does not compete with CDNs because it is specifically optimized for use with Silverlight RIAs.
Why is this service branded with Windows Live?
This service is part of the Windows Live Platform.
It's free—what's the catch?
There is no catch. This is a new offering designed to accelerate the development of the next generation of media rich applications.
Can I tap into other Windows Live services?
Yes, customers are able to use Windows Live ID and other Windows Live APIs today and in the future. Silverlight provides a great platform to consume these services.
Do you support digital rights management to protect my videos?
In the future, Silverlight Streaming will provide support for DRM-encoded video as an optional paid turnkey offering.
What applications will Microsoft provide to make hosting easy?
Microsoft is building a simple uploading tool and working to add publishing support directly to Silverlight Streaming via Expression Encoder, a feature of Expression Media. In addition, third-party companies are adding support to their own applications for Silverlight Streaming.
How is my content secured?
You will have to be signed into the Silverlight Streaming service to manage your account and your Silverlight applications. Your Silverlight Streaming account ID and secret key, associated to your Windows Live ID, will authenticate you as the unique and legitimate owner of the applications and content you upload to the service. You will also need Silverlight Streaming account ID to render your applications on your Web site. The Silverlight Streaming ID is public. However, the secret key should be kept confidential.
How do I get started?
To sign up for your free account, visit silverlight.live.com. Anyone with a Windows Live ID can participate.