What do the [] brackets mean?
Square brackets (also called brackets, especially in American English) are mainly used to enclose words added by someone other than the original writer or speaker, typically in order to clarify the situation: He [the police officer] can't prove they did it.
What are [] used for?
Brackets are symbols that we use to contain "extra information", or information that is not part of the main content. There are two main types of bracket: round () and square []. ...