This is the official manual for the latest Org-mode release.
Internal links (see Internal links) will continue to work in HTML. This
includes automatic links created by radio targets (see Radio targets). Links to external files will still work if the target file is on
the same relative path as the published Org file. Links to other
.org files will be translated into HTML links under the assumption
that an HTML version also exists of the linked file, at the same relative
this translation. ‘id:’ links can then be used to jump to specific
entries across files. For information related to linking files while
publishing them to a publishing directory see Publishing links.
If you want to specify attributes for links, you can do so using a special
#+ATTR_HTML line to define attributes that will be added to the
<img> tags. Here is an example that sets
style attributes for a link:
#+ATTR_HTML: :title The Org mode homepage :style color:red; [[http://orgmode.org]]