Brackets

Use brackets ([ ]) to enclose material in a quotation included by someone other than the writer, such as editorial additions or comments.
• In the newspaper, I read, “The strong earthquake in Washington [State] caused extensive damage.”
• The lecturer noted, “In ancient Israel, a trumpet or shofar [ram’s horn] was blown on Rosh haShanah, the first day of the new year.”
Use brackets to enclosed parenthetical matter within other parenthetical matter.
• After the tire rotation and balancing (done at the service station down the block [the mechanic appeared to be very inexperienced]), my car pulled to the right when I drove.
• The external rectus (ER) muscle (sometimes referred to as the lateral rectus [LR] muscle) turns the eye outward.
• For his birthday, he wanted a new toolbox (along with a new fishing pole [his good one had broken]).