Man

From Grokdoc

Man is a console based utility that you can use to find out information about many of the programs installed on Linux.

'Man' (lower case, no speechmarks) is short for Manual.

As an example, suppose you wanted to use the console based email program mutt, but didn't know much about it. You could open a console, type in 'man mutt', and the manual pages for mutt will be displayed. Pressing the cursor keys, or the page up and down keys will navigate the manual displayed, and pressing 'q' will exit the manual and return you to the command prompt of the console.

As a rule man can a useful first step when finding out about a program in linux, or a handy way of recalling that tricky command line option you just can't remember.

Man is from a time before the internet, so if you have a web connection, it's probably easier to google for an answer to your problem. In fact most man pages are duplicated on the web now anyway. In spite of this, man still remains a fast and useful reference utility.

See also info.