List Changes"" report - what exactly does it show?

I have a very basic question but for some reason I can't find it in the Online Help or existing community post (please point me in the right direction if I missed it). Basically, I wanted to know what exactly determines what shows up in the Changes report, or specifically, reports with this option checked "Display only new or changed records". 

What I mean is, what is the definition for 'new' or 'changed'? Is it 'changed since I last logged into the app'? Is it 'changed by anyone' or just 'changed by me'? How long does it 'stay' on that report? For example, I made some changes yesterday, but my List Changes report does not show it anymore. Is it because it's just by 'day' (if so, then the question is what timezone)? If I can get the exact parameter/definition of how the system considers what is 'new' or 'changed' and therefore show up on the report, that would be great. 

On a related note, I'm asking because I want to schedule a report that basically shows all the changes since the last report run. Is this the List Changes report? If not, is it possible to create a custom report that will show only changes to the table since the report was last run (and then schedule that to be sent via email)?