Here is a common definition of a background process:
"A background process is a program that is running without user input. A number of background processes can be running on a multitasking operating system, such as Linux, while the user is interacting with the foreground process Some background processes, such as daemons, for example, never require user input. Others are merely in the background temporarily while the user is busy with the program presently running in the foreground. So that other process can be sleeping and taking up swap space, until activated, which thus makes it currently a background process."
Given that definition, wouldn't that make a process like apache2 a background process since it never interacts with user input in terminal? And wouldn't that consider most process background processes, since most processes running on a system do not deal with user input in the terminal? Oddly enough, I personally wouldn't consider apache2 a background process since a user does interact with it through http requests (just not a terminal).