Asterisks | Indicate a point of repeat. Here are some examples:
( ) Parentheses | Set off stitches that are worked as a group; may be used for explanatory text.
[ ] Brackets | Set off stitches that are worked as a group; sometimes used with parentheses when there are two groups of instructions nested within each other.
Crochet Shorthand | Used occasionally when the meaning is quite clear.