Top displays the top processes on the system and  periodically
updates this  information.   If standard output is an intelligent
terminal (see below) then as many processes as will fit on the
terminal  screen  are displayed  by  default.   Otherwise,  a  good
number of them are shown (around 20).  Raw cpu percentage is used
to  rank  the  processes.

WWW: http://www.groupsys.com/top/