I was writing up a signpost support question on our site meta. That post included a link which would need to be updated to another such question once asked. I therefore wanted to include an HTML comment:
<!--- An HTML comment ---!>
Except that including it broke the formatting from that point on:
Here, after the comment, *formatting* does not work. [Links][1] formatting don't work, And even paragraphs can't be made with double line-breaks. The comment itself behaves correctly, which is to say that it isn't rendered. You'll sort of have to see the source code to see exactly what is happening, and do take the above comment out and see what happens (i.e. that the formatting fixes itself). [1]: http://www.example.com "example link"
<!-- this is a comment -->
while<!--- this is not ---!>