Help:Why isn't my wiki formatting working?

Why isn't my wiki formatting working? There are a variety of possible reasons:

• See Help:Using greater-than and less-than symbols and HTML in wiki articles
• A space at the beginning of a line turns the line roughly into the equivalent of an HTML <pre> tag and also turns off the interpretation of beginning-of-the-line characters. For example, the following, if left-justified, would be a bullet, an indented line, and a subheading; but, here, they're each indented one space (click edit to see this) and so display like this:

*
:
==test==

• You can use HTML commenting in a wiki page--unless you forget to terminate the comment correctly.
• Failure to correctly terminate bold (with three ticks: ''') or italic (with two ticks: ''), especially if both are used together, can sometimes make it look as if the formatting problem is later in the text than it actually is.