upper layer data: for network necessary applications. this is what the user uses to interact with the os. i.e chrome, firefox, outlook, etc.
where the application using the network resides, common network applications include web browsing, e-mail, file transfers, and remote logins.
layer 5 in internet model, the software that enables the users to perform useful work  ex) instant messaging, videoconference, file transfer, email, web, wordprocessing