Square brackets

Also called brackets.

How to type it

[ is the right pinky; ] is the right pinky.

Common uses

• Writers use square brackets to add their own words inside a quotation, as in "she [the mayor] agreed".
• The Latin word [sic] in brackets tells readers that an error appeared in the original text.

Less common uses

• In many programming languages, square brackets pick an item from a list, as in items[0].
• In Markdown, the text of a link goes in square brackets, followed by the address in parentheses.
• In chemistry, square brackets around a formula often mean its concentration.