Sections are like different chapters of a big book, each one specific to an aspect of the system. Some commands might appear indifferent sections, so you might need to specify which section you are interested in.
Sections are numbered
9, and there's a 10
th one, called
n. You can
a to display all matching sections for a
given man page. If you omit the
section parameter, the
first matching man page is displayed.