In UNIX computing, the system load is a measure of the amount of computational work that a computer system performs.
An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs.
In most Unix-like operating systems, the ps program (short for "process status") displays the currently-running processes.
A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification.
Uptime is a measure of the time a machine, typically a computer, has been working and available.
The standard Unix command who displays a list of users who are currently logged into the computer.