I was trying to update .net version and packages for an old project. when I wanted to update them I see a message that say "Package Source Mapping is off." with a configure button that let me add it.

I see this https://learn.microsoft.com/en-us/nuget/consume-packages/package-source-mapping and watch the youtube video in the link but still It's completely unclear to me.

So my Question is:

• What is package source mapping in simple term?
• What is the benefit of using it over not using it(importing packages normally)?
• What is supply chain ( is it just multiple packages in general or it has a deeper meaning?)
• how package source mapping will Safeguard supply chain?

or if you want just one particular question: Why package source mapping exist? (in a simple yet complete form)