Emphasis

Emphasis

single asterisks

single underscores

Supercalifragilisticexpialidocious renders italics within a word using single asterisks.

Supercali_fragilistic_expialidocious doesn't render italics within a word using single underscores.

Strong

double asterisks

double underscores

Supercalifragilisticexpialidocious always renders bold within a word using double asterisks.

Supercalifragilisticexpialidocious always renders bold within a word using double underscores.

Literal asterisk or underscore

*This text is surrounded by literal asterisks*

This text also has a literal asterisk here * and two here **.

Extra spaces

** Double asterisks ** and __ double underscores __ are displayed as literal characters if accompanied by extra spaces.

The same is true for * single asterisks * and _ single underscores _ if accompanied by extra spaces.