Difference between SDK, Toolkit and runtime?

Question

What is difference between a SDK, Toolkit and Runtime patch of any kind of software like Silverlight.

Answer 1

Programmers:

• SDK: Software Developer Kit - only interesting for programmers
• Toolkit: extra tools for the SDK, to help developing

Enduser:

• Runtime: minimum enduser plattform files, to get the software running - not the endsoftware itself!