Every version of UNIX comes with an extensive collection of online help pages called man pages (short for manual pages ). The man pages are the authoritative source about your UNIX system. They contain complete information about both the kernel and all the utilities.

A page in the HP-UX Reference. Man page references take the form title( section), where title is the name of the page and section is the section in which the page can be found. For example, open(2) refers to the open(2) page in section 2 of the HP-UX Reference. Or use the man(1) command to view man pages, for example, man open.

a document written using the Unix "man" macros, which are themselves written in the NROFF/TROFF text processing markup language

a concise description of how to use a piece of software, intended to be read using man or one of its work-alikes