This is the official manual for the latest Org-mode release.
Up: Internal links
Org can automatically turn any occurrences of certain target names in normal text into a link. So without explicitly creating a link, the text connects to the target radioing its position. Radio targets are enclosed by triple angular brackets. For example, a target ‘<<<My Target>>>’ causes each occurrence of ‘my target’ in normal text to become activated as a link. The Org file is scanned automatically for radio targets only when the file is first loaded into Emacs. To update the target list during editing, press C-c C-c with the cursor on or at a target.