the Latin word for ‘so, thus’, is added in round or square brackets after a quoted word or phrase about which some doubt might be expected in the reader's mind, because of a misspelling (which the quoting writer does not want to correct) or some other error of use:

The Abbey PR office phoned to issue a statement: ‘Abbey is committed to providing it's (sic) customers with good service, and we apologise if on this specific occasion we fell below our high standards’

Liverpool Daily Echo, 2007

, drawing attention to rather than silently correcting an erroneous apostrophe. (But if the Abbey office issued the statement by telephone the error must have been in the newspaper's own transcription in any case.) It should not be used as a supercilious comment on the quoted writer's style or supposed looseness of grammar, as in the following example:

I probably have a different sense of morality to [sic] most people

Chicago Tribune, 1994, quoting Alan Clark.