A newer form of online help is the info command, which replaces the boring, linear output of the man with a navigable, hierarchical set of documentation.
As a test, try reading the info page for the ls command itself:
$ info ls
Once you get into the info system, you really need to remember only a few keystrokes:
TAB: go to the next sub-menu on this page (all submenu links are identified with leading asterisks)
n: go to the next sibling documentation node (go to the right)
p: go to the previous sibling documentation node (go to the left)
u: go to the parent documentation node (go up)
q: quit out of info
If you really want to learn more about info, read its own info page:
$ info info