What is the URL field for in Note properties?

Desktop version here… You are looking at a note and click the (i) icon at the top (Note properties)

What is the URL field for?

Note: RFE-ish that I think I posted elsewhere (probably github) … I would love to see word and character count here. UPDATE: https://github.com/laurent22/joplin/issues/160#issuecomment-489735470

It’s automatically used when the clipper clips a page and creates a note.

But you can also use it to reference a page of your choosing manually.