What is Silverlight? (In one sentence, in an interview)

Question

Consider you are in an interview for a .NET/C# job, and are asked:

What is Silverlight, in one sentence?

EDIT: OK, some took it the funny way:-) I have accepted one of the more serious approaches though. However, thanks to all posters.

Answer 1

Microsoft Flash.

Answer 2

It's a framework for building interactive applications for the web, desktop, and mobile devices using .NET technologies.