What is “runlevel”?

reference link:http://en.wikipedia.org/wiki/Runlevel The term runlevel refers to a mode of operation in one of the computer operating systems that implement Unix System V-style initialization. Conventionally, seven runlevels exist, numbered from zero to six; though up to ten, from zero to nine[citation needed], may be used. S is sometimes used as a synonym for one of … Continue reading What is “runlevel”?