Man pages

man pages are the electronic documentation that comes with every Unix system - the "manual pages". They are accessed with the command 'man'. You'll sometimes see a number written after them, such as "sshd(8)" or "ls(1)". The number corresponds to the section of the manual in which the particular page may be found. This is important because some items may be in multiple sections.

Usage:

man sshd

man 5 hosts_access

man 3 hosts_access