What is Silverlight?
Microsoft Silverlight is an application framework for writing and running “rich” applications and media playback in the browser, or as a separate application (out of browser). Similar technology from other producers includes Adobe Flash. Service providers who use Silverlight are, for example, Netflix, TV2 / TV2 Sumo, Viaplay and Altibox. Today, there is only one browser that supports Silverlight – Internet Explorer.
See a list of browsers that support Silverlight: https://en.wikipedia.org/wiki/Microsoft_Silverlight#Supported_platforms
Silverlight and Compello
Compello used Silverlight for parts of the functionality of our Compello Invoice Approval solution. We are in progress of updating our solutions with other technology; HTML5 and WPF (Windows Presentation Foundation). We currently offer our approval module in HTML5 and soon, the WPF bookkeeping module will be launched.