In computer science, a type signature or type annotation defines the inputs and outputs for a function, subroutine, or method.
In window operating system, a window service is a computer program that operates in the background.
It is similar in concept to a Unix daemon.
In multitasking computer operating system, a daemon is a computer program that runs as a background process,
rather than being under the direct control of an interactive user.
A background process is a computer process that runs behind the scenes without user intervention.
Big wheel means a person with great deal of power or influence.