Notes in a Nutshell

[Account Closed]

I kind-of understand what notes are, but as a Millennial I'm prone to distraction and misunderstanding if the exact answer I'm looking for isn't immediately found on one of the first three links Google provides. We are conditioned to understand concepts if there is a 2:00 video that illustrates the idea with friendly images and that generic guitar strumming in the background. 

There's a book on flipping, wholesaling, and land lording here on BP, but is there something on buying notes and/or can you explain what they are and how they work (without using legal-ese or advanced financial vocabulary) in a nutshell? Thanks.