How does one backup a database using the export utility?

Oracle exports are "logical" database backups (not physical) as they extract data and logical definitions from the database into a file. Other backup strategies normally back-up the physical data files.

One of the advantages of exports is that one can selectively re-import tables, however one cannot roll-forward from an restored export file. To completely restore a database from an export file one practically needs to recreate the entire database.

Always do full system level exports (FULL=YES). Full exports include more information about the database in the export file than user level exports.