From anywhere in Vim, execute
:help :help. This will open a horizontally split window with the manual page for the
:help by itself will take you to the Table of Contents for the manual itself.
Vim's help files are navigable like regular files (you can search for keywords within a file like normal, with
/), and additionally they are linked together by tags. Jump to the destination of a tag with
Tags are words surrounded by pipe
| characters. Versions 7.3 and up 'conceal' those pipe characters (
:help conceal) and highlight them.
For example, the Table of Contents page shows the following. All of the words highlighted in blue are tags and are surrounded by pipe characters. Typing
CTRL-] with the cursor on
quickref will take you to a useful page with a list of tags to useful Vim features.