Different ways to get italic formatting?

Question

Seems familiar, doesn't it?

But when I type something like this
Italic was caused by a pair of single *
since it should be pair of double **

Is this normal?

Answer 1

The formatting help page gives these examples:

*This is italicized*, and so is _this_.
**This is bold**, and so is __this__.
Use ***italics and bold together*** if you ___have to___.

which render as

This is italicized, and so is this.
This is bold, and so is this.
Use italics and bold together if you have to.

So: one asterisk or underscore for italic, two for bold.

The small box in the sidebar only gives some examples of markup, it is not a comprehensive reference.