At the top of your reply box there are a number of editing tools. Click on the cogwheel and the option ‘Hide Details’ appears. This will set any text in a Summary box which can then only be read when clicked.
Important: the cogwheel is only available when your reply box is not in preview mode!
Summary
Example
Sooner or later there will arise a need for this option when discussing a recent film, book or show. Please consider to make use of this feature when chances are not all our fellow members are familiar with a recent work.
Inside the designated spoiler sections of films - currently we only have one for BOND 25 - spoiler tags are not necessary. Therefore, if you prefer not to know about certain details, leaked or otherwise made public, you might want to avoid the spoiler section.