The term 'daemon' is used for processes that performs service in background.
rather than under the direct control of a user.
Unix processes works either in foreground or background. A process running in foreground interacts with the user in front of the terminal (makes I/O), whereas a background process runs by itself.
In a Unix environment, the parent process of a daemon is often (but not always) the init process (PID=1). Processes usually become daemons by forking a child process and then having their parent process immediately exit, thus causing init to adopt the child process. This is a somewhat simplified view of the process as other operations are generally performed, such as disassociating the daemon process from any controlling tty.
