This is the official manual for the latest Org-mode release.
Org mode uses begin...end blocks for various purposes from including source
code examples (see Literal examples) to capturing time logging
information (see Clocking work time). These blocks can be folded and
unfolded by pressing TAB in the begin line. You can also get all blocks
folded at startup by configuring the option
or on a per-file basis by using
#+STARTUP: hideblocks #+STARTUP: nohideblocks