I would like to put some notes on org document which should not be printed/ exported to pdf . Is it possible?
See the manual: C-hig
Lines starting with zero or more whitespace characters followed by one
#and a whitespace are treated as comments and, as such, are not exported.
Likewise, regions surrounded by
#+END_COMMENTare not exported.
COMMENTkeyword at the beginning of an entry, but after any other keyword or priority cookie, comments out the entire subtree. In this case, the subtree is not exported and no code block within it is executed either1. The command below helps changing the comment status of a headline.
C-c; - Toggle the
COMMENTkeyword at the beginning of an entry.
1 For a less drastic behavior, consider using a select tag (see Export settings) instead.