What you put in a
topic/
post/
node before you reveal
anything that might
spoil the experience of a
play/
film/
book/
game for
anyone reading your words, who has not
experienced what you are writing about.
A courtesy usually found in
Movie threads where those who have seen the film want to
talk about it, but don't want to give away a
surprise in the film.
In
forums where
html is allowed a
spoiler is often
coded in white so you have to
run your mouse over the words to even see them.
The spoiler alert is usually
ALL CAPS to make sure someone knows a spoiler is ahead.