This declaration corresponds to the center environment. This
declaration can be used inside an environment such as quote or in
a parbox. The text of a figure or table can be centred on the
page by putting a \centering command at the beginning of the
figure or table environment.
Unlike the center environment, the \centering command does
not start a new paragraph; it simply changes how LaTeX formats paragraph
units. To affect a paragraph unit's format, the scope of the
declaration must contain the blank line or \end command (of an
environment like quote) that ends the paragraph unit.