Bracket completion is a visual tool that the editor view uses to indicate you
which bracket matches which. If you open any .tex file,
and select any bracket, whether it be a parenthesis (), square brackets [] or braces {}, the
editor will highlight the bracket and its match in yellow (this default color can be changed).
So, for example, if you position the cursor on the braces in
\section{Introduction}, you would see
\section{Introduction} in the default yellow highlight,
showing you the location of the beginning and ending brackets.
