Square brackets [ ] are used when we want to make it clear that we have changed a quotation.
They make the quotation clearer:
- The witness said, ‘He [the man in the blue coat] had stolen my wallet.’
They are used with sic to show that a mistake in the original quotation has not been corrected. Put [sic] after the mistake.
- The police said, ‘They made there [sic] getaway in a fast car.’
(there/their)
They are used to add words missing from the original quotation:
- John asked, ‘Is it [a] good question?’
