Silverlight

Silverlight is a deprecated framework from Microsoft for building rich internet applications. Introduced in 2007, it runs as a browser plug-in and provides a XAML-based user interface model together with a managed code runtime compatible with a subset of the .NET Framework. Developers wrote applications in C# or Visual Basic .NET, with the UI described in XAML and the logic executed inside a sandboxed plugin. Silverlight supported multimedia playback, vector graphics, animations, data binding, and a range of controls, with integration to web services and network resources. Applications could be packaged as .xap files and delivered through a web page.

Runtime and development: The Silverlight runtime consists of the plug-in component and a cross-platform CLR that executes Silverlight applications in a restricted environment. Development was primarily done in Visual Studio using Silverlight Tools, targeting Silverlight 3 through 5. UI was defined in XAML; the framework provided controls, layout, animations, data-binding features, and access to data services via WCF or REST endpoints. Silverlight 4 introduced out-of-browser mode, allowing standalone execution when installed on a user’s system, with its own windowing model and trusted security settings.

Platform and decline: Silverlight was supported on Windows and macOS via the browser plug-in, in environments that allowed such plugins. Over time, major browsers dropped support for NPAPI-style plugins, reducing Silverlight’s reach. Microsoft and the broader web community increasingly favored HTML5 and JavaScript for rich internet experiences. Microsoft ended active development and support for Silverlight; the final releases culminated in Silverlight 5, whose end-of-support occurred in October 2021. Since then, Silverlight is considered deprecated and is generally not recommended for new projects.