What is Managed/Unmanaged .net code and what difference does it make to me?

I see the terms managed and unmanaged used a fair bit around here. Searching online I can get a fuzzy notion of what they are, but what I really need to know is how it affects me as C# desktop app developer? How do I know which I'm dealing with at any point and how does it change my approach to that code?

Duplicate

http://stackoverflow.com/questions/334326/what-is-managed-unmanaged-code-in-c

From stackoverflow

• Managed code is code that needs the .NET framework to run... unmanaged code doesn't. If you are writing code in C# you are writing managed code. You might interface with unmanaged code if you use Pinvoke, but if you stick to pure C# your application will be all managed code.

  Robert Gowland : @Jon T: Thanks, Jon, that's the nice succinct sort of answer I was looking for.