copy and paste only preserve the content, but not the context. u cannot go back to the original content u copied from.

That might be true in a browser context, but I think both Windows and Linux (not sure about macOS) has the concept of a "clipboard" owner or "controller", which is usually the last application that copied data to the clipboard (although Linux also have the concept of "primary" and "secondary" "clipboard"), so when someone pastes into a application you're writing yourself, you could see where the data is coming from. Of course, you wouldn't be able to see what data the data that was made into the clipboard was derived from, but you get a bit of context at least.

Edit: Actually, my memory about how it works on Linux is a bit foggy, only part I'm relatively sure about is that Windows has the concept of clipboard "owner".

I have once used an app (forget name), which can track down clipboard updates. I uninstall the app mainly because I cannot go back to the "context", only knowing which app the data is from is not enough. For example, I copy a sentence from a chrome to word. There is no url for me to reopen the website.

Thanks!