Hi,
Some apps store what they have done in temporary files that are dumped when the app is closed.
The purpose in many cases is to allow for Undos to take place.
In System Preferences > General pane you can set the number or remembered item that can be shown as "Recent".
This can be Server, Documents and Apps.
Servers are literally any other computer whether it is a server or not in the IT sense.
Documents are anything an App can open. So Pictures and Preview "Documents" Many apps will have a Recents option in the file Menu.
The Apps part explains itself. However the Apple Icon top left that has it's own Menu has a Recents option that shows all the lists. (or if like me, who has 20 as the set figure, as many as will fit on the screen)
for the
Points.

7:59 pm Friday; August 24, 2018
iMac 2.5Ghz i5 2011 (Sierra)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
MacBookPro 15" 2016 (High Sierra 10.13.x)
Mac OS X (10.6.8),
iPhone 6 iOS 11.x and an iPad (2)