Most users of the roff language employ a macro package to format
their documents.  Successful macro packages tend to ease the composition
process; their users need not have mastered the full formatting
language, nor even some of its major features like diversions, traps,
and environments.  A familiarity with some basic concepts and mechanisms
common to macro packages (like “displays”) remains helpful; this
chapter aims to bring you to this level.  If you prefer a meticulous and
comprehensive presentation, try gtroff Reference instead.